Would that be the 8553PT Perma torque? I have a set of these and am trying to figure out piston to head clearance on my set up. After searching it seems they are lots of results between .045-.053"
Or are you referring to 521SD? Can't seem to find much info at all on that one.
There visual appearance seems different than the OP's. Maybe he had .039" or even thinner, in which case that would be a simple fix with the right head gasket. The 8553PT might be enough, either way he needs to figure out how far out of the hole those pistons really are.