Not sure how much help this will be, but I will throw in my two cents on this one. Had a 1964 122S that had a simular issue. In my case I replaced the upper and lower control arm bushings, shocks (front & rear), and ball joints. The car not only sat better, but the streeing and handleing was vastly improved. The only thing I wish I had done was to replace the springs. I know that the newer spring provide a much better ride, but I think a really good used set, like the four on e-bay right now, could also improve the picture.

Hey you are going through the motions with the bushings, save yourself the headache of pulling the front end apart again and replace as much as possible while you are there.

Good luck

Oliver
66 1800S