Hi from the UK!
It sounds like you are already hot on the case with what parts you need. The early R65s being shorter of swingarm, subframe and smaller front wheel, thinner forks. 45 and 65 engine also having different barrels, heads and shorter pushrods.
There are lots of similarities on the common lumps for 80, 90 and 100 (frames, gearbox, engine casings) but then myriad little changes such as centre stand, gearbox and crankcase improvements like diode board mounts. The early R65 frames are 'the same' as the bigger ones and the bigger engines fit. You'll find different subframe mounts or rear foot pegs etc.
Find out exactly what bits you can get and someone here will definitely know what fits what.