Weird thing about the GT40X heads... they come in 64cc and 58cc. The 64cc was suggested on a 302 because they use flat-tops w/smallish reliefs. The 58cc were to be used on 351W cause they use dished pistons.

 

That makes no sense as the 78-up 351's used the same 64 cc heads the 302's had.I would opt for the 58 cc head, no matter which displacement they were to be used on. My Canfields were 64 cc til I milled em .060 to bring em down to 57ccs

 

Changed my mind and cancelled the twisted wedge heads today. Gotta save a few more $$ to get some AFRs.