Yes and maybe. I've seen references to a liquid cooled 300cc CG motor on Taobao, so you should be able to find a larger cylinder and piston, and maybe a larger crank for peanuts.
I doubt that you'd find a more aggressive cam profile, but you could certainly give it to a cam grinder. You could buy several (again on Taobao), so that you're not sacrificing your existing cam.
Open this link in Google Chrome:
http://item.taobao.com/item.htm?spm=a230r.1.14.41.EwbYM4&id=26436512698