I bought a set of 15x7 Cragars used which fit fine on mine. I don't know the offset though I do know the wheels came off a '55 Chevy sedan delivery, and the front and rear required different offset to make them work on that car.
If I were spec'ing wheels one of the things I'd think about is getting the middle of the tire at the point where the center line through the kingpin hits the pavement. Doing so makes the steering effort less, and the wider the tire the more it matters.
