Pipes are steel. I have enough trouble welding that. Black paint is to disguise the crappy welds. :-\ I have no idea where to start with Ti. There are a few Ti bolts on the bike though and a modified GSXR alloy steering stem pressed into a modified RD bottom triple clamp. Front caliper is an aluminum replica with custom aluminum pistons hiding inside.
On the Taco, you should be good with air cooling for short runs. Try to avoid firing it up until you are ready to race ie push it to the line - warm it up a little before and then leave it until the run. Jet it a jet size rich and use lots of oil in the pre-mix.
I usually start with the coldest plugs I can get and then I set ignition timing and first pass at jetting. Then if there is no evidence of the side or center electrodes overheating, start going one heat range cooler at a time until you see the right heat signature.
Not sure what carb you plan on running but keep in mind that a 4 stroke type emulsion tube runs leaner than a 2 stroke type as revs rise. And taller spray bar also runs richer at the top end than a low spray bar - according to Mikuni.
Chrome moly. What's that? No. the back end of that frame is all heavy Japanese steel. No ThyssenKrupp 4130 here. Nothing to see here. Move along.
Try Onlinemetals.com for 4130 tube. Really thin wall cracks easily and doesn't like to be bent, so choose a reasonable wall thickness. And what I think is reasonable and what you are comfortable may not be the same but it will be a lot less that a street frame for a chopper might be. Weight - or lack thereof is important in acceleration. Not an issue for LSR racing but accelerating mass takes more energy, so for a given amount of energy, the lower the mass, the more acceleration is available.
Co2 bottles are lighter but a PIA to get refilled, so build a refill station if you get serious. Otherwise, buy them prefilled. https://www.sodamod.com/4oz-Tank-Pre-Filled-with-Beverage-Grade-CO2-p/co2_4ozfilledwco2.htm A 9 ounce bottle is easier to fill and is easy to hide, but with regulator, it's about as heavy as a standard air bottle. What were we saying about compromises and optimization?
And if speed at the deep end isn't much over 80, you can use cheap skinny moped tires with low rolling resistance. And remove the bearing seals at least on the inside of the wheel bearings and machine up alloy wheel bearing spacers but add 10 thou to the length compared to steel.