The 440 based 505 is probably the easiest combo. 4.250 stroke, good rods, shelf pistons, etc. Add Edelbrock heads and pick the right cam and you'll easily make 600+ HP.

Here is a shot of my 505 on the dyno. I'm running a M1 intake manifold, 1000 HP carb, and a Comp solid flat tappet. This engine makes about 650 hp in this setup.