You could always have a stock 4" or 4-1/2" wheel cut down to 3-1/2" wide at a cost of ~$125.00. That would probably be about 1/2 the cost that you may wind up having to pay for an original 5 on 5-1/2, 3-1/2" wide wheel. I have seen some originals listed and sell @ $300.00.
I have no idea where you are located but these people can cut and reweld a wheel for you and no body else but you would ever know the difference.
Wheel Works PO box 130, North Florence, NJ. 08518, 609-499-2233, Excellent service.