We're getting ready to finish the custom headers for a customer's BBC/Feuling headed combo and I need to have a set of custom copper gaskets cut for the Funky Feuling Flanges. Before I go out and get some copper that is too soft or too hard for gaskets, I figured I'd tap into the collective knowledge here. So, what kind of copper is best for header flange gaskets? TIA!

Hank