Custom ground camshaft, low power

20% IMO is unacceptable on a fresh engine and the main reason why you're seeing the power down. If you saw the vapor being pushed up and out, the intake valve(s) are leaking. I think at minimum the heads need to come off and be done properly by a performance shop. Had your shop pulled the springs and checked the pattern they would have seen it. Never mind using a runout gage on the seat or valve and measuring the guides.