I hear you on the parts search fun. I tell people that 'Restoring (resurrecting) a basket case motorcycle is like putting together a 3,000 piece puzzle... but the pieces are scattered everywhere'. Also, 'A puzzle won't let you ride it down the road'
Re: Hop-up. I sent my 62' 175 Scat motor to Mutt a few years back for a re-build. I included a 'stuffer plate' I'd rescued from a trashed 'racer' motor. After he put it in, Mutt realized the carb required an oversized jet and different jet riser tube (more holes) from a different carb to run right. This means the motor was looking for more fuel to air; this means a stronger motor.... just from a stuffer plate. I'm VERY pleased with the results (but also understand the limits of 1962 H-D Lightweight technology). Ha!
Have fun putting together a
Race Motor; and I wish you the best. Be sure and include a set of Racing Gears when Mutt gets them done. If I had them in my '62 Scat (First, second, third... instead of first, second, fourth... I'd probably go up one tooth on the engine sprocket and add a repair link to the chain for running around town and the backroads here in Western Pa.
70; and the 15 year old still lives when riding these motorcycles.