Pre 09 5.7 blocks can go 4 inches in bore but its best to have it sonic checked to be for sure. Will require a custom piston at this time till others start really doing it. Andy at pwr has one running for a few years now on his own vehicle i was told by him. Cylinders are still thicker than the 6.1 as well.

Again sonic testing the walls is best when taking that much material out.

Im doing a 4" 5.7 05 block with eagle heads an 80mm billet turbo.