i just found out that your dohc heads has less cc in the combustion chamber than that of wrx heads. So the sti block with your heads wont be like 8.1:1 comp. It'll be a lot higher than that- most likely 9.5:1 (guesstimate). Also the top of your pistons from your old block has the same as the wrx's. call me

 

on another thread about clearance issues.

San

 

I think its ok to use the dohc head gasket for clearance since its made out of metal it should handle the added pressure.