Well if you are using a head gasket that thick, you have no quench. This will be even more prone to detonation. I am not sure how far in the hole your pistons are but, with the .051 head gasket they need to be .006 out of the hole to give you any quench.
Since you have to buy new pistons, may I suggest something? Buy a "D" dish piston that will give you a true 9.5 -10:1 with a tighter quench, run a head gasket that will put your piston .035-.045 from the head. This will help prevent detonation and you will have a better performing engine.