look at the combustion chamber side of the 261 head,there should be a steam hole in between the combustion chambers, roughly an 1/8 inch or so in diameter i think. what i did was i took the new head gasket,it will have these holes already in it, i used it as a template on the 235 head, center punched, then carefully drilled the holes with the proper size drill bit, be carefull not use to much force, wouldnt want to break the bit off in the head. i believe the 235 head i used was from a 1956 engine.
