The steel "Rally" wheels from a Chevy K5/Blazer will fit. They're 6 lug, 15" x 8" wide. Backspace is 3.5" so they clear the stock steering arms OK. I have these wheels fitted to my '50 truck, the wheel rims clear the 12" disc brakes I have fitted without a spacer, and although they are wider than the stock rim, they still clear the wheel arches.
Stuart.