Figure your compression ratio, with those rods and pistons. Might be on the high side for a turbo application. I was running "O" rings and a solid copper gasket at 10-12 lbs boost and 8.0-1 CR, because I was blowing stock felpro gaskets. Problem was not the CR or parts or boost. It was detonation that I wasn't aware I was having.
The "O" rings and gasket requirement depends on CR, and boost level.