The wheels were never staggered as built by MaMopar. Someone swapped them in. Most slanty cars got 4 1/2" wide wheels. V8 cars often had 5" to 5 1/2" wide wheels.
Dusters, Demons and Dart Sports need wider wheels out back to fill out the wheelwell.
Nice score on the car.
That's what I was thinking, but the strange thing is the previous owner ran the same size tire all the way around. Maybe he thought it would look cooler! It sure helped getting those tires to fit though.