that's weird because there is no 1983 cb750 (not in this country anyway, there is an 82 and then the nighthawk).
the short answer is no.
The long-ish answer is that the headpipe spacing is different. I have heard of guys tweaking the head pipe spacing and using the stock collars but the rear mount won't bolt on. Remember: with a chop saw and a welder anything will fit.