Been digging around, nothing stock was made with this backspace it seems and the only aftermarket steel rims are Bart circle track racing units with 7/16 lug holes.
I may get a set of "police wheels" done by Stockton.
I have a set of four BBP 15 x 7 slot mags with a rear space similar to what you want. I can't remember exactly what they are if you are interested I will dig em out and measure. They are Shelby Cal 500's in real good shape.