Pat, first thing I think I would do in your case would be to change out the front or rear rotors to a matching bolt pattern. If you have drum on the rear, then quess you would need to change out the front rotors to match. Also, if you have a traction lock rear axle you should be sure to keep the spare tire heigth the same as the rear tires you are running.

I've set my studebakers up all ford bolt pattern and have kept the rear tire height the same as stock tire (mainly to keep the stock wheel well filled as it would be with stock tire) Stock studebaker bolt pattern is same as ford bolt pattern and I just carry along a skinny stock bias ply for a spare on long trips in a bag. Bias ply do not mix well with radials and it isn't pretty, but will get you to the next stop if needed. I also carry a plug repair kit and a small 12 volt compressor.