Are they 8 inch wheels? 4 1/2 back space with a 1/4 inch spacer. gives a 4 1/4 back space. 4 1/2 BS on an 8 inch wheel is a centered wheel. An 8 inch wheel measures 9 inch outside to outside. So a 4 inch BS leaves 5 inch outside
4 1/4 back space fit on the inside with 8 inch wheels. What I found is a 7 inch wheel gives more tire bulge then an 8 inch. The wider wheel sometimes works better.
Years ago I had swingers . 7 inch wheel with 3 1/2 BS would rub the quarter with G 60's . An 8 inch wheel with a 4 1/2 BS same tire G 60 didn't rub the quarters but I had to move the rear clamp on the leaf spring.
These are very old pictures both these cars had 8 inch 4 1/2 BS wheels . I have pictures of several more early swingers and GT's I had and I used these wheels on several. Of course we always lifted them back then. Late 70's early 80's. Darts are narrower then the Duster and Demons. That is why I always liked the Dusters and Demons. Barracudas are also narrow . 8 inch wheel with 4 1/2 BS is the widest you'll get on and still have to roll the lip a little and get very close to the leafs. Pics of some of my old cars with these wheels from back in the day.