If it has a keyed shaft, you should be able to put the clutch on the shaft. I dont know the outside thread pitch of the engine I'm using, or the length of the shaft, I just know its long enough to put a clutch on. As far as speed is concerned, just remember this. It doesnt matter much what engine you use, speed is determined by gearing. an engine that is geared too high can actually end up having a lower speed, but an engine that is geared low enough will operate at a decent cruising speed, and depending on what engine it is, will have a decent amount of torque as well, especially if its a 4 stroke. you can take a 79cc or 99cc engine and gear it for about 30-32 mph if you wish, and it should clim hills pretty good. I'm gearing my engine for 31mph @ 5000 rpm, which is probably its safe limit. if you are only going 30mph and pedaling away from stops, the cops shouldnt bother you too much.