Alot of fun stuff you can do with that. I would start with a 440 kit, MRD/SSW pipe, FCR 39 carb. That's should liven up the motor a good bit. I'm pretty sure that bike takes everything the 400sm does.
you can pretend you're Knotcher
http://www.youtube.com/watch?v=Nrq31J6RbgU