SB Advice.

The best swap for cheap power is to get a low mileage 5.9 magnum ($400-$800) with a 650 and a airgap they dyno 320hp with headers probably 300hp with manifolds add a healthy cam you got 400hp. I got 5.9 Jeep it pulls pretty hard in a light A body with a free flowing intake and exhaust would be a rocket.