15" wheel size for 60 Valiant

All,

I'm getting some 5x4 to 5x4.5 adapters for my 60 Valiant. Going to be keeping the stock drum brakes for now and going with some 15's in the front to match my rears. Can someone say what width and backspacing will work? A 5 1/2 inch width steel wheel? I have a 8 3/4 rear end with 15x8's. The front has some 13's on it as you can see in the pic. I don't like the look and want to fill up up the front wheel well. I have found some used steel wheels and believe that they are Mopar types.

Thanks,
Marion1960 Valiant Front.JPG