in the mid sixties I used a '54 pass 235 head on a bored '59 261, used the 261 head gasket and I did not drill the head-- the car did run hot and was a real pain to start with the '54's 6V system. Later in the late '70s I bored a '62 261 and ran a 261 gasket, but used a '56 truck 235 head, again no holes drilled. The truck ran cool as a cucumber. Up to now I had never heard of drilling these steam holes, and knew several others who ran them undrilled as far as I know. And running the pass heads was the trick thing to do for increased comp. ratio. Wish I had another, just to hear the Smithys converse with one another...oh yeah and the cop! ("les' hear 'em boy-- step on 'em---yeah, oh hell yeah, jus' sign here--have a good day now") Yeah right.
As they used to say in Hot Rod Magazine, "Some times you eats the bear, sometimes the bear eats you".
