I think that is right. Any chance you sonic checked the bores on the replacement blocks. I have never had a 54 early 55 261 block but was told that the original cast blocks could take a larger overbore because they had thicker cylinder walls. Would be curious as to whether the replacement castings were done on original tooling with the thicker cylinders (does not seem so with the later style mains) or the later thinner cylinder walls.
