as i understand it (and i do NOT claim to be an expert, but i've been reading a lot), these engines use stellite valves and unleaded gas is no problem at all. it seems like i've also seen that there isn't much room to work with regarding bigger valves, and people tend to stay stock. i also think edgy cams does custom work to whatever your heart may desire.
good luck, and keep posting! i will probably be tearing into mine late this spring.
