B body rear in 69 Dart

Dealing with this myself this week. Recently bought a 72 Duster and when I put wider tires on the rear it was then noticeable that the rear was shifted over more than an inch to the Passenger side. Starting measuring and then figured out I have a B Body rear 8 3/4 also. Spring perches were not moved just the springs spread out. I can see that most of my bushing are shot and it allowed the rear shackles to move enough on both sides to bend toward the pass side pushing the tire past the wheel opening. I can bet that over time yours will do the same and get worse. I'm taking it all out and moving the spring perches and replacing the bushings and shackles.