On our previous blog, we started the idea of building a budget-based Gen III 5.7L motor by combining a 5.7L rotator package with a 4.8 or 5.3L iron block. The key to this is a bigger bore. This bore increase is roughly 0.110 inch, but our sources tell us the iron motor cylinder walls can accommodate this—but you should sonic-check the block. Shoot for a wall thickness on the thrust side (inboard side on the driver side, outboard wall on the passenger side) of between 0.200 and 0.240 inch or more. You will also need to upgrade to a 5.7L head gasket since the 4.8/5.3L gaskets will be too small. This idea will not work with the 5.L aluminum block nor will boring a 4.8 or 5.3L out to the 6.0L 4.00-inch bore size. The walls will be too thin. What you will end up with is a 5.7L motor that masquerades as an iron 4.8L. Pocket-port the heads, add a camshaft and a carb'd intake, and you've got an easy 450hp engine for little money.