Mantree,
I think you’ll find the rear disc on the cb750 f’s (F0,F1,F2,F3) all shared the same rear disc with the 77&78 GL1000s. The rear dual opposed caliper kit was still available for the gold wings but not for the 750f’s when I did my 76f1. I used the old gold wing kit on my f1, but I’m remember there was something extra included that the 750f don’t use or the gl has something different or extra but it didn’t prevent rebuilding the F1’s caliper.
And like all ready mentioned the early Fs 75/76 had spokes and a single K front disc. The later Fs 77/78 had front dual discs and smaller calipers. Both different than early Fs and K’s… The dual disc on the F’s may have been borrowed or shared with the GLs but I’m not sure without looking the part numbers up..👀