I recently acquired a 302 and the guy didnt build it and the number he gave me to the builders did not work, I pulled a halve cover and and found a few things, they are cast iron and have the number OK17 between the first and second set of valves on the upper part of the head....then I found a cymbal between the last set of valves on the upper part that showed "CP" the spark plugs are angled and the rocker arms appeared to be stock and are bolted in not studs. I did not find 302 or 351 wrote on them or GT40 or anything else......just OK17 and CP... I did fin that they have large hexagon shaped freeze plugs on the heads as well....I dont know if thats normal or not.