I have a 1998 ts770 with a trashed engine. Rather than buying a rebuilt or new 770 which I've heard are money pits, I'd rather put a cheaper 640 in it that I found at a bargin basement price. Does anybody know if this is possible without large mods? I don't mind mixing and matching exhaust and intake parts or carbs ect. I am getting the complete 640 ski, so I'll have everything from the 640 as well including computer and such. Any information would be awesome before I dig in and try this. Thanks!