My "750" is a '75 CB750F SuperSport as it was called. As I understand it the '75 and '76 (F or F1 - what ever you want to call them) are mechanically identical. Just changed the chain on mine, end of last season, still have the box. Size 530 chain, 102 link. Now my bike is completely original, I don't know about yours.
If you feel that you need a stronger chain, there are specialty chains available in the same size or if you want a sealed chain, many of the O-ring or X-ring chains have a higher tensile strength.
If you maintain the chain regularly and replace when worn I see no reason to throw a chain. I think that the chains today are just a little better than what was supplied as original equipment in the '70's.