is this a numbers matching 383 that you are wanting to beef up on the down low? Otherwise a 440 crank in a 400 block (can offset grind the crank to get 470 cubes) and it'd be a killer with the right equipment and it'd bolt right in to your current 383 brackets (ps/exhaust, everything). The only exhorbitant expenditure is the KB pistons and the special crank grinding & you'll be doing some of that anyhow