I had a kit on my 7 for a long time.
Very fun on a bike that weight about 65 pounds.
Any av7 kit will fit. You will need to get a tunable carb (dellorto SHA should work fine), you need to know what the hell you're doing.
The kits are hard to find. The malossi is out of production (I seized mine badly). Mopeds are also fun at 33MPH.