Does your Duster "float" at highway speed?

Power steering I assume?

The stock steering boxes always have that "over boosted" feel to them. You can adjust the pressure put out by the pump by adding spacers to the pressure valve. Some people have said it really changed the feel of the steering. On my stock box, I didn't notice any change by adding shims to the pressure valve. I sent my Dart's steering box to Firm Feel and they rebuild it into a stage 3. I have not driven the car yet to feel the difference though.

That might be what you need to do. Have your box rebuilt and go to a stage 2 or 3. Then you can fine tune it if needed with the pump shims.

I have the Stage 3 box, you're going to love it. Buy a 900 PSI Saginaw box and its like a manual rack in a light car but with enough assist to parallel park with one hand.

To the OP, if its a totally stock power box it will be way, way,way over assisted in an A-body with a light nose. It was way over assisted in my dads Coronet 500 with a 440, can't imagine in a light nosed A.