[patrickt]

Most of us have the different dyno software programs. If you keep the displacement at 425 cubes, the compression ratio at 10.25 to 1, and use "large tube headers through mufflers," it's almost impossible to tweak the heads, induction, and still use one of the vintage Ford cams (even the big ones) to get everything up to 500+ horsepower. Don't take my word for it; try it yourself.