Don't have to be an actual Ala D'Oro, like I say. A re-badged "Harley" sprint, maybe even a 250cc and dig up a big-bore kit for it? People are making replica parts for that. And then the replica frame. Build the wheels from scratch, replica bodywork - That's how probably 99% of the "Ala D'Oro" models out there on the road got started. It's not like they're actual works racers, bought out of the lovingly doted on collections, dredged out of mothballs and stuck on the road for some young adrenaline addict to thrash. Gawd, how I WISH. There ought to be a charity organization doing nothing but exactly that.
No seriously though - these days, you see parts from Green-Frame Ducatis like their wheels with the Borrani rims with the correct four-digit NUMBERS stamped on the rim (denoting nothing but that they were drilled to suit the hubs in question, when a MODERN wheel builder like Buchanan's would do the job a thousand times more accurately!) selling for easily TEN TIMES what it would cost to build 'em from scratch from brand new Grimeca hubs and either NOS and/OR new production replica rims. Same deal with vintage 4LS drum hubs - wheels listed for somewhere in the area of TEN GRAND - just the friggin' one front wheel! Meanwhile, that's only talking about a Fontana 210mm drum, practically a 200mm Suzuki 4LS like I've got for the Kid's "KZ440LOL" in real world terms - But you can buy a full-on Magnesium 250mm Fontana with the air-scoop type side-plates, for well under THREE TO FIVE grand, then an additional two-hundred to five-hundred bucks MAX, for the spokes and an NOS rim. Talking like a beat up old used & rusted, clapped-out USED wheel, for more than double the value of the brand new one with stainless spokes & super-accurate rim drilling. As compared to how the vintage rims used to be done - three sizes, for disc hubs and 100mm-ish drums, for 160mm-ish drums, and 200mm-plus sized drums. Cost extra if you're drilling for a conical hub. The four-digit "CORRECT" rims denoted nothing more than that they were made for that specific hub - but it doesn't mean there's anything else different about it. And seriously - them Grimeca DISC hubs are RIDICULOUSLY CHEAP compared to the replica DRUM hubs. Talking like ... people have paid more for HONDA CB750 hubs, from what I've seen happen on eBay.....
But yeah, if you really wanted to do it up right, all you're really looking for is an ENGINE for a donor bike! The rest of it is out there.
Check out MOTOCICLI VELOCI MILANO - IMHO the far better source than even DISCO VOLANTE MOTO - they're both decent sources for vintage race parts. But Veloci seems more oriented toward the Aermacchi Ala D'Oro. They'll even BUILD the damn things for you, have had 'em listed for sale over & over again.
The awesome thing about doing it this way however, is there's nothing being CHOPPED UP as you say. Maybe a couple of beat up old engines that are in desperate need of being rebuilt anyhow - What's the harm in that? I suppose it would leave a bunch of spares left over, one whole transmission and cases, at least - But that's the cost of rebuilding ANY engine, is that there are gonna be damaged parts rejected from a build - Ergo, any left-over bits that are perfectly useful, are gonna help somebody fix up another one. IMHO it's a win-win. Ditch a decent SPRINT frame that's not heavily rusted & all clapped-out? Pass it on and replace the one that IS wrecked. It's All Good, Man.
Now I can't speak to the final costs of such a project, especially given the need for the one-off replica modified crank-case stuff. Let alone the replica one-off FRAME for the same. However one thing is for sure - it's gonna work out better than the original collectors' bikes. Well, IF they're properly appraised for their own intrinsic historical value that is. Plenty of vintage bikes AREN'T. But give it another few years and they'll ALL be worth more than it'd cost to build 'em. I mean, look at what's happening with the GODIER VINCENT, or the SUNBEAM S3 - people dug out the old tooling & ran off another series of parts.
I'd like to think it could be done with EVERY old bike factory. Like - like those old Soviet small-arms factories that were moved whole-sale to China & other up & coming Communist super-powers. Just box up all of the factory machines - or at the very least, the jigs & other tooling which was specialized & used upon those machines - box 'em up and stuff 'em into some dusty garage, LABEL EVERYTHING, go up into the office and box up the blue-prints & production plans - give the youngest yet most knowledgeable factory floor employees a lifetime contract for free room & board so as to preserve the unwritten knowledge - Then in another generation when they want to dig it all out again, it's a turn-key business.
But even if it ain't, people have still figured out how to do it - like those replica Honda RC-series DOHC-5 & DOHC-6 racers. Took a whole TON of research to get the replicas right. Though for all intents and purposes, it would have taken LESS research to make the parts more durable using MODERN methods, to copy only the exterior shape of the engine but to build it the new way - Of course, this would affect the final running SOUND and FEEL of a bike - all very important when it's the motorcycle equivalent of the STRADAVARIUS VIOLIN! Cello I suppose, if it's an RC-181.... But yeah, replicas can and should be made with newer and better components - witness the CBR250 based RC-replicas. Let alone the CBX and DOHC CB750K based Hailwood replicas, or my own "CB900K0 Bol Bomber" effectively two CB450K0 Black Bomber engines strapped side-by-side. (Well, in terms of power output per litre displacement, they're the same! Except that my rebuilt motor puts it more in the category of two CB500T's strapped up tight....) Or somewhere down the road, when I manage to pull off a batch-produced replica of the alloy CB1100R gas tank off of my "Bol Bomber", (polished up "toaster tank" style, of course) AND some Comstar rims with lighter replacement hubs and Akront NERVI rims for wider tires etc, somebody will be able to take a 2010+ CB1100 and make a replica of either '81 or '82/'83 CB1100R - built up to modern specs of course. Though I suppose more modern bike fans would rather see a replica frame kit of the "CB1100R" PROTOTYPE from the 2007 Tokyo Motor Show.... Either way: There IS a place for all of that stuff. And it's my earnest hope that the net effect of it all will be that the NEW bikes will come out with the retro-fried aesthetics to compete with the original classics for our hearts & minds & wallets. Needs to happen with CARS too. Though it's a tough row to hoe, when the current version of the "MINI" is bigger than my lil' GRRRL'z Toyota Yaris. They need to make a Fiat 500 and Morris Mini that's scaled right, down to the size of the originals. But if at least the mainstream models could once and for all ditch the TUPPERWEAR design philosophy. Not the plastic - plastic is your FRIEND it helps to shed weight and helps to extend the lifespan of components - if it's the right kind of plastic that is. But yeah, it's the DESIGN sensibilities that they need to bring back from the dead. To get rid of the "carved from a block of cheese" computer design aids. Dig out the French Curves from mothballs. If they can pair that stuff with the new generation of ELECTRIC vehicles, then they needn't push the tech to the point where electric cars compete with the ridiculous horsepower of modern sports cars - Just make 'em the same power & weight of the vehicles from the era that their aesthetics wish to emulate, and people might just settle for another Carman Ghia - I mean, why NOT? It would be a real win-win. Build 'em to fall apart like the formula-1 racers, and stuff 'em full of air-bags, and there'd be no need for all of the heavy steel unibody cage construction anymore, 'cause they'd probably be safer than modern cars. Especially when the big heavy shit is no longer on the road anymore, and they needn't fear being crushed like a bug on the windshield of a HUMMER or some such.
Well it will certainly happen with bikes before it happens with autos. But I welcome it. ALMOST went out and bought the new CB1100 instead of a '79-'83 model, but after a long time shopping I found just the right complete package in an '82 CB900F - And there aren't enough aftermarket upgrades for the new bike - YET. There will be SOON though. Much as a vintage DOHC-4 enthusiast might feel compelled to kick the tires on the new bikes, there couldn't be a new Honda model more welcome to the vintage scene, IMHO - If it's truly successful, maybe the REST of Honda's model line-up will henceforth carry forward the vintage aesthetics. Yeah, I'd much rather see them same beautiful sculpted fins dressing up a liquid-cooled max horsepower flagship CBR series monster, but this was a good place to start!
Who knows, maybe some day the Aermacchi twins will make it to new production? Not just the twin SPRINT head four-strokes, but the Grand Prix liquid-cooled Too-Smoke models as well?
Best thing they could do? ANY of those old vintage companies, and the people who hold the rights to them? Do what Honda did with it's Cub & CB125 engines, and let the Chinese set up factories copying all of that vintage tech. North Korea if needs be! ANYBODY - so long as it means replica Aermacchi engines coming back into production. Would be nice if HONDA themselves could take something away from this lesson, and the next time they give old engine plans to a brand new factory? Give 'em the plans for the RC-181 - let the Chinese pop off thousands of copies of THAT engine. Probably the one and only engine that this MIGHT happen with, would be if the Enfield India factory popped off some Rickman Interceptor twins - You can really see that they were thinking about just that, with their new Café Racer model. Even so - I'M not holding my breath for ANY of that stuff to happen. People being what they are.
A person's just gonna have to whip up their OWN dream bike. If you want something DONE, gotta put in the work yourself. But it doesn't hurt to borrow from elsewhere, to "stand on the shoulders of giants". Which is why ANY vintage race-bike that I might want most in this world, I'm looking to the cheapo 2nd-hand '80s HONDA models for engines in a similar configuration!
-S.