Since you told me via e-mail that the virgin 383 (presumably matching numbers) is still in the car, I’d sure remove it and park it, sealed up, in a corner of the garage. Then, if want some real HP out of a B-engine, find a clean used 400, add a stroker crank, and have at it.
Depending on heads, cam, manifolding, etc., 700 HP isn’t difficult. A nice mild 500HP 496" B-engine would be a pleasure, even the least expensive aluminum heads would get you there (440source.com).
Much above that power level you need a single plane manifold.
The carb: If Holley, be sure it is vacuum secondaries. My choice: 800 CFM Ed AVS.
There’s no shortage of Mopar-specific machine shops to help you with anything you need, from a rotating assembly to a drop-in complete engine.