383 vs 400

MyBlueCuda said
I've had both motors. The 400 is a dog. It was basically a de-tuned motor to keep the government happy.
I had a 1964 Plymouth Sports Fury with a 383 4bbl automatic that ran high 14:00 in the quarter that was completely stock.
Versus a 1972 Dodge Charger with a 400 Magnum automatic that ran 17:00 in the quarter bone stock.
The 400 Magnum has a real crappy intake manifold. It has an internally built in E.G.R. valve that hurts performance. On top of that is the Thermo-Bog carburetor! Never really was too impressed with that carb.
If you can find a rebuildable 60's 383 with small chamber heads I think it would be the way to go. The 400 may have a larger bore but I'd bet on my old 383 every time.

That Charger was probably 500-600 pounds heavier than the Fury in addition to all the emissions crap and low compression. That's not really a good comparison. This Duster is obviously not a factory correct, stock restoration, right? Who runs the stock intake manifold anyway?

The only real downside to the 400 is that it probably has a cast crank. Depending on what the OP has planned for this car, it may or may not be a problem. A set of closed chamber heads will bump the compression up nicely for street use.