where you gonna fit the expansion headers.... this should be interesting.
I probably would have hunted for a 2000,2001 CR500 engine. Just seem like you would have more room to work with, but i don't know dimensions just guess. Or if you have $6200 buy a brand new CR500 engine
http://www.servicehonda.com/new-motors
or just the whole bike for $12k and say screw the street project i have 500cc of stroke craziness for the dirt.
http://www.servicehonda.com/honda-2010-models/500af
excuse me i need to go to the ahh... bath room, i need alone time.