Back in the mid 80's I ran a pure stock L-88 427,12.5:1 pistons and square port heads and it was all balanced. But I added a hugh .775 lift crane cam,triple springs,holley strip dominator intake with a 1050 carb. I buzzed it to 8,500rpm and it held together for one race season. The cam was way to much for the engine but it sure sounded good. Looking back I was very lucky the thing didn't split in two.