talk to the guys at Cometic Gasket.
I don't happen to have their number with me but, you can use google to look up their website and get the contact info from there.
I got mine from bender. That was a 96 vmax 600. A great improvement for the buck and easy too. Also do a search on things I've posted. I think I've mentioned things before. Yamaha made a comp-up kit for the 96vmax which included a thin head gasket, jets, clutch springs,and weight rivets. If ya need a part # I may still have it. Just let me know.
he isn't talking about the 500's. The 500's run a lot more compression than the 600's, and aren't safe to add any more to. The 600's on the other hand have a lot of room to improve, a lot of performanced left on the table with the stock gasket.