What difference in compression from .40, .51,.60, .74.. 6.0 iron block 408 with afr 225 heads. Custom wiseco pistons .was shooting for 9.5 don't want to go higher a bit lower would be ok also.

 

The problem with simply going to a thicker gasket is it also increase the volume in the quench area, which can lead to detonation. I'm guessing that you are going with a FI setup, but I wouldn't go thicker than 0.060" in order to avoid detonation.