What wont ?
maybe left foot shift bearings are differant dia. but a few thou can be machined of to fit the early bearings.
72 crank with square counterweights on flywheel is 72% balance , but differant frames like differant %adges, maybe.
Just use a large oil pump. Had one on a T100 of a 750 someone (Livingston) reversed to fit .
Maybe the oil pump holes are a over t .reversed .
Setting up the cams and followers deserves a bit of care ,Needle roller bearings , same as box , can be used .
73 750 Valves CAN be used in 8 stud heads. Theres a few castings , maybe the available ones ARE the replacement for the Crack prone ones.
70 heads biggest ports .in a T120.
69 Commando / atlas points housing and Electronic ign .? Though a good Mags fine. pre 56 they had a smaller output shaft, which will shear .
see if you can find a set of W&S valve sprins . set for Yam XS 500 & 750 4 valve gets you all sorts of fancy bits, seats , caps , shims. They fit Commandos too . . .