Them DR650 rear hubs are such a compact lightweight rear disc hub, WITH a cush-drive, suitable for a Classic Superbike rear disc conversion - I only wish there were a decent version which looked more period-correct, more like the FONTANA rear disc hub from Jack Findley's TZ700 racer, or similar. There just aren't anymore of the old "quick-change" or "SPOOL" style rear disc hubs anymore. It's a pity is all, 'cause you can have the period-correct thing OR you can have a lightweight compact readily available & inexpensive rear disc hub - but you can't have both. Well I mean, even if it weren't cheap, if it were a pain in the ass to throw it all together, but you could still find a decent lightweight compact rear disc hub which weren't such a boat anchor like the period-correct vintage SUPERBIKE rear hubs, ie KZ1000LTD or GS1000 or CB750F1, something closer to them in style but smaller & lighter - One POSSIBLE alternative might be the Y2K+ Kwaka Vulcan 900 Classic rear hub, but I'd much prefer a 40-hole spoke-count. At a minimum. Where do you even GET shit like that anymore? Buchanan's Spoke & Rim used to make a replica of the BARNES quick-change hub which the flat-track people loved so well - I suppose the closest thing to that, would have to be the old chopper type Harley pattern SPOOL hubs, and adapt a decent disc and a cush-drive onto that.
And there are sooo many Harley pattern RIMS out there - I've even snapped up a few SUPER-MOTO rims which have 40-spokes & are drilled to suit the Harley rear hub. For like, $39.99ea for 4.25x17" & 5.0x17" back when the seller didn't realize what he had on his hands. Said he had a whole WAREHOUSE full of the things! See, if people were SMART, and they had shit like that kicking around, they'd make a KIT - you'd have a Suzuki version a Honda version a Kwaka version maybe two to suit their 6-bolt vs 4-bolt dual-disc front hubs - You'd use your OWN rear hub of the OEM type for your given bike, and they'd sell you a bolt-up cush-drive & a rotor spacer with a spoke set. WITH the rims, of course. Maybe even a bracket for the OEM calipers to suit the smallest period-correct OEM caliper, like the 276mm or better yet 260mm even 240mm front rotors from smaller Honda models. And analogous stuff for the Kwaka or Suzucchini or whatever.There'd be a lightweight rear disc-brake conversion on EVERYBODY'S Classic Superbike if there was shit like that available.
Then we could take these heavy-as-shit '75-'76 CB750F1 rear hubs & 296mm discs and use 'em for a boat anchor or to weigh down crab traps or as a garden ornament or some such shit! Ha-ha.
-S.