Free US Mags...will they work for me?

You could use the rears with a narrowed rear axle. Maybe you could find another set of fronts with better specs.
Or, I could use the fronts, with the 3.5" bs in the rear of the dart to shove the tire outboard and get the same size tire and wheel with a 4.5" bs for the front. This would give me, I think, a modern look and solve what I think was one of the biggest design flaws of cars of this era, the rear tire tucked too far under the car. Doing this gives me the look I'm after, while not spending the money on a narrowed rear end.

I 'may' end up turbo charging the 6, but not for many years to come. I don't ever see me truly needing the rubber that would fit on a 9" rim other than to meet some sort of aesthetic. So, a ser of 7" rims all around is more practical, but spending less money on this toy has its practical side as well.