A-body chassis dynamics, handling

They're all pretty much the same basic design and similar weights, so what works on one A-body will work on another. Most of them have quite a bit of rear overhang. I don't have any numbers for the Duster, but it's not significantly different from other A-bodies. I've seen Darts and Dusters built for handling as well as Barracudas.

Shock absorbers are designed to damp out that wobble motion. The best ones will do this without contributing excessive harshness to the ride. I have a set of KYBs, and they improve handling over stock, but they also make the ride a lot rougher. I've heard good things about the Edelbrock IAS line for a street car, and would probably use QA1s if I were buying shocks for a handling car, but I currently don't have any personal experience with either one.

Good sway bars should make quite a reduction in body roll; I'm running an Addco front bar on my Dart and it really reduced the body roll in spite of a rather poorly designed mounting system.

If you were hitting the bump stops on corners, you'll probably be able to feel it. Not necessarily as a bump, but as the car stiffening up suddenly. And you have other problems. If the car has been lowered, it probably needs stiffer torsion bars.