If you opt for the north/south FWD like from the Caddy or Olds Toronado, you can use relatively common engines like the Cad 425, 472 or 500, or a Pontiac 400/455, or an Olds 455, or a Buick 455. For that matter, w/just a relatively inexpensive adapter plate
, you can bolt up a Chevy V8. You'd want something w/a lot of torque, at least a 383/400 SBC or preferably a 454-plus BBC.
How is it that you have come to the idea of cutting this car up to make it into a franken-mobile?