Don't forget, the bigger engine will more than likely contact the back of the front fender. Alot of people stretch their frames 2 or 3 inches. Most exhausr pipes aren't an exact fit and require some "fitting". Alot of the pipes that do fit, tend to be on the smaller side and don't let the engines breathe very well. I guess it really depneds on what you feel like tinkering with. They are not a 100% bolt and go deal though.
Nicholson 500x (Project)
Nicholson 185s
Nicholson 110 (That takes an atc70 tank)
Ascott 500 head/350x (Project)
Homebuilt Racer Chromoly Suspension 110 (Ragin Runt)
PK Racing Suspension 70
A+ Inc Suspension 70
AWS Aluminum 90 frame
Hi Performance ATC Suspension frame rd350
Hi Performance ATC Suspension frame 90