how much cam with performer rpm heads?

If you get sneaky, you may be able to get an inner spring to boost seat and open pressure. You need to have an idea regarding desired camshaft to get a good answer.

Get with a good machinist that knows these heads and they can guide you. The advertised max lift is a joke with these, they won't handle an aggressive camshaft with that lift.

ou812, Brian, on this board is a good guy to talk with.