Picked up my 360 today!!!!!!!

the builder simply took the actual chamber volume of the head-64cc, added 5cc from pistons valve reliefs, then added the 8.9cc that the head gasket adds and =77.9cc
I believe he's using the felpro 1008 head gasket that has steel crush rings to better support/back up the fire ring and gasket itself against higher than 10.1 compression engines. The felpro 1008 adds 8.9 cc with its .039 crushed thickness and 4.180 bore diameter.