Advice asked for widthening rims on a 70 Duster

the 15in ralleys, and the 14in ralleys have the same dia center stamping. I sent a set of SBP 14in ralleys to Willamette Wheel in Portland 40+ yrs ago. I don't know if the are still there. They cut the centers out of the 14's and welded them into some blank 15in rims. voila. 15x7in SBP ralleys.