My specs for a GMC 270 bore for .060 over is 3.836-3.838. Call Craig at Grant Rings. He was able to put together a set of standard rings for a 228 that I am building for my employer, and he may be able to help you out. 1-714-996-0050.
Joe
just retired and finally making headway on my project truck. 1940 GMC AC152.
