Please post photos of your fabrication table, frame jigs, and mig and or tig welder. Brazing is an option.
Buddy of mine stuffed a 212 predi in a Nel Lusso frame by creative modification of the seat post tube. Comet clone transmission. Went like a scalded cat until the stock Huffy rear coaster brake did a grenade lock-up.
Been awhile since I had seen so much raw flesh.