Don't think a pipe from a triple will be correct for a 500 twin. Sure it might physically fit in there, but I don't think it would run that great. There's a reason pipes aren't universal. By the way, our first snow over here was like Oct 17th or somewhere around there.
1974 Arctic Cat Cheetah 340
Gonna be set up for ice fishing. Should be good for it's purpose!
Most snowmobile problems are caused by a loose nut connecting the handlebars to the seat.