1972 Duster Rim and Rubber combo

I second the 15 X 8 size rear wheel with a 4.5" backspacing. That will look nice and shouldn't rub. I think this wheel would work with or with out the adapters just fine.

Fronts like you said as small as you can get maybe 5" width
Backspacing shouldn't be an issue with any standard production wheel unless it is made for a low rider