The stroke and pin height on a 292 is definitely different than that of a gmc 270, so the pistons for a 292 will not work without modification. The 292 that I mentioned above is the displacement of a 270 that has been bored to 3 and 15/16, which should also be considered a maximum bore for the 270. My guess is that if it was possible to get 302 cubic inches out of a 270, Bill Fisher or Frank Mcgurk would have done it.
Talk to Patrick Dykes or Tom Langdon. I remember reading about Langdon's 302 that has been punched out to 340 or something like that using more common v-8 pistons and rods. Machine work would have to be done on the crankshaft, cylinder walls, and head for that to work. If anybody would know it would be Tom. It has been said that he has forgotten more about the 270 than most will ever know.
