A body with New Challenger Wheels

I have been thinking about wanting to put the New ALCOA wheels from the new Challenger on my 74 Duster. They are 20x9, but I am not sure on the back spacing. I currently have a Ford 9" uder my car with 15x8" and 29x10.5 Tires.

What would I have to do for the rear if anything to make these fit?
What would I have to do to the front if anything?

Does anyone have these on thier A Body? if so can I see pics.