mercrusier made a 4 cyl copy oo the chevy 2 engine that was cast iron and the head was cast iron as well it was the head that we used on the midgets because it had dividers between the intake ports and the stick chevy2 's did'nt ., but that being said I think the block you have is a Fontana aluminum block that he made with ford part numbers years ago it was for a drag racing class and had to have the Ford part numbers on it . Midgets also used them with ford heads as the bolt pattern was already there without altering the block .Ricky Johnson 602-723-0554