steering and handeling help, 73 duster

From everything I have read, and experienced, unless everything is factory spec stuff, like rubber bushings, etc, you will have to "tune" your suspension to your car. Thats why this time around, I purchased tubular uca, adjustable strut rods, boxed my lower control arms, and my k-member is completely welded and reinforced. I will also be getting solid tie rod sleeves with the bigger 11/16 tie rods, and using a tubular lower radiator support, inner fender to firewall reinforcements, torque boxes, and subframe connectors. Case in point, almost all ps boxes move because the k-member itself flexes. You can stop that by reinforcing the k-member. Our cars are 30+ years old, they are no where near as tight as they used to be, so regardless of the parts used, unless you reinforce them, you will have flex and variables. Maybe I am being too picky lol. I just think it best to start with a good solid base, meaning the reinforcements. You can buy the k-member reinforcement kit from firm feel.
I also agree with pretty much everyones ideas, checking toe, etc. I had a Dart that sat like yours, and handled exactly how you described. Honestly, same situation, all new parts, etc. I never got it to handle good. I suspected it was because of the difference in height from front to rear, but I knew nothing about handling at the time.
Good luck!