My recommendation would be to get a baseline servicing completed, get it running and enjoy. I own an un-restored, original 1973 R75/5 for my daily rider. These /5's are wonderful motorbikes when you learn to handle and adapt to some of the primitive limitations. I see your bike has the original silver-turned-to-gold intake tubes, a fine and rare detail. If it has the 64/32/9&10 Bing carburetors, you have a well sorted machine on your hands. It's a thing of beauty. I am sure Lew would agree.
Ah,...I see it has the 2 screw dome topped Bing carbs. You will have no trouble with them, but not original in the purist sense. I recently bought a 1971 R75/5 with those carbs. They can be made to run just fine on your 750. If the bike has had regular service, they are almost certainly well sorted.
Hi James, thanks for the post. I didn't realize the original silver turned-to-gold intake tubes were a desirable thing .... I learned something already. So do you think my carbs are not original to the bike? I must say you are all having an influence on my approach to this machine. Thinking .....