Looks like you have a V75, 4 valve heads and 750cc. It had a small fairing like a T5 and a 16inch front wheel. You are not in NZ by any chance? One of these was for sale on trade me recently. I have a V75 brochure from the 1980s and considered buying one but instead purchased a Lario which I thrashed the hell out of and had no trouble. I sold it before the mileage got high, but a friend told me that it rattled its way up to 65000km. I don't no if the valve gear was ever updated. It got wrecked in a crash.
Cheers, voncrump