I saw a guy installed one on a Nevada 4.0 (same frame, smaller wheels and cheaper components). It looked tight but did fit. As far as the fat bottom tube I'm sure I'll figure it out, I'm pretty handy. My frame is a size large so that's in my favor. Regardless I'm looking forward to jumping into this next week. Hopefully all my parts arrive in time.
Ordered the 66cc with the following upgrades;
Rse high comp head
"Boost bottle" with billet 40mm intake
And "designer bicycle" sprocket hub adapter w/ 40t sprocket.
Royal purple 2 stroke oil (all I run in my vehicles, including my vette)
Spare gasket set and piston
Tungsten bit set for porting
After it's broke in and if get the motor dialed in I'm hoping for 35-40 mph top speed.