"Lumpy" Steering on 1970 Dart Swinger

You may have jammed the column down to far and the reaction rod is having a hard time. Loosen all the column retaining fasteners, and the floor-plate. Then gently tug the column to the top. Then slide it down . Then find the center somewhere and secure it there. There are three bolts that secure the column. Sometimes the lowermost one has to be shimmed so as to keep the center shaft aligned with the box.The floor-plate is tightened last.
Then make sure the wheels are pointing straight ahead when the steering wheel is centered half-way between the locks. I assume you found the master spline on the top of the steering shaft?
If that doesn't solve it, you will need to get the front wheels in the air and check the steering box for self-steering, and if you have any, you will need to center the control valve.
If centering the valve does not fix it, or if you are unable to stop the steering from self steering then the box is bad.
There is a sector-shaft adjustment in the box, and it is easy to tighten it too much. And if it is done without first centering the steering box from lock to lock, then you will get the symptom you describe. This is the number one go-to actually to correct this symptom. You didn't by any chance mess with that adjuster did you?lol.