I second the cast iron bell housing but would use the truck one as it takes easier to use motor mounts. With the rear mounts on the bell housing you can use front mounts on the engine which is sometimes easier. IIRC the 454 doesn't have drilled and tapped front mount holes but does have the flat spots so do your own. I am using my last iron bell housing on a Mercruiser (Chevy II) engine that's going into a 1928 Chevy dump truck and will for sure have to pick another one, or two, up at a swap meet. They are handy for use on the engine test stand and the horizontal mount starter has saved several engines with broken a starter mount ear.

Evan