Anytime you disassemble an engine the deck becomes warped and distorted and should at least have a cleanup cut done to restore it to being flat and square. Its kinda' like the torque plate thing with distorting the cylinders to simulate the head being on the block when its bored.
As for the head gasket, you have never made a true 15 psi of boost on this engine that it didn't hurt something. Once you get to a point of containing all that cylinder pressure and don't ruin ring lands, you'll find the weak link in the chain real fast.
