I can understand your determination here, once you get an idea in your head, you just can't let up; it's a bit like dropping a 350 chev into an old F100, most people would say "WHY THE HE// WOULD YOU WANT TO DO THAT?" & that's exactly why, because it
shouldn't be done...
Your idea goes against every logical argument:
-a high powered engine in a small kart
-simply
using a
snowmobile engine in your climate? what?
Wich leads me to: Not only will you have trouble
sourcing an engine, I feel you may have problems
running it. Snowmobile engines are, quote obviously, meant to run in cold climates & since you live in a slightly warmer climate, you may very well have overheating problems... not that I'm trying to deter you, I just want you to
think about it...
Here's a few I found in a quick search:
http://westmd.craigslist.org/snw/4523684415.html
http://fredericksburg.craigslist.org/snw/4523053825.html
http://winchester.craigslist.org/snw/4498138232.html
Somehow, I don't think you'll do much better... unless you're prepared to travel or pay the difference in shipping costs...