New car- Need Advice

After a long search, I finally found a A-body that wasn't roached or with an astronomical asking price. Original California car brought to Memphis in the 90's and been garaged ever since.
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Before I can drive it, I need to address the tires which also date to the 90s. I would like to upgrade the rear wheels to some 15x7 and run 245/60/15. Every thread I can find on this combo , people seem to be running at least 4.25 backspace. Wheel Vintiques must have changed suppliers, as they only sell 15x7 with 4 backspace now. Any other sources of steelies with small bolt pattern? The rear is 7.25 if that plays into it at all.