why didn't you use a y8 head instead of going back to a z6?? it seems like something got damaged along the way.. make sure ur block is in good condition and that the head gasket and head bolts where torqued down to specs.. i think comp for a mini me is around 11:1 if im not mistaken and if i am someone correct me, thats using a y8 head gasket for higher compression.. good luck...