I've ran copper heads gaskets for many years, 25+ and never blew a head gasket. O-ring the block, use studs, and use Hylomar around the water jackets. They don't require a special RM finish like cometic ones do, better heat transfer between the block and head, nearly impossible to burn out or blow out, re-usable, can get them in any thickness you want, hold torque values better than regular gaskets. Can't think of any reason not to use them in a high compression high horsepower high rpm smallblock unless you are starting with everything brand new and can machine the heads and block for the multi layer type gasket.