Here is a blower piston ( 8.9:1 ) with a quench area for a closed chamber Magnum head. Zero deck and .040" MLS gaskets gives .040" quench area. FYI, if you are running an open chamber cast combustion chamber head and a raised ( above deck ) piston in the quench area, measure carefully! The piston quench dome often has to be cut and the combustion chamber quench area can very due to casting irregularities. You will surely ( and don't call me Shirley) need to know your head gasket compressed thickness.