Wheel & Tire Combo for ’74 Duster

I want to put Chrysler Rally wheels on my car. Fronts will be 14 and 15 on the rear. My question is what combo can I run without any modifications to the car itself. The 14 is available in a 6" and that is what I want on the front. The 15 is available from 6" to 8".

Thanks for the help.............