408 vs. 440: Which Would You Choose?

Doesn't take much to make 425-450 with a 408, either. Stock magnum heads with a decent valve job/bowl blend, performer RPM airgap, 750 carb with 1" spacer, 1 5/8" headers, and a comp cams XE284H (maybe even XE274H), 3.91 rear would get you there and keep a decent idle.

Don't really need forged crank/rods/pistons for that power, so the bottom end wouldn't be too much. Cast crank can be found for around $300.

Trying to help the guy get there with what he has rather than have to start all over.