4.25 back space on a 8" wheel is not enough for a GM A body.. 5.25 is more like it.. The Cutlass in the photos has 15x8 with 5.5 back space.. 255/60r15 tires also..
I would use stock 15x7 rallys with 225/70r15 tires.. The stock wheels are hub centric..
The Parts Place is the only company that sells correct fitting hub centric wheels for the GM A body. They only come in stock steel though..
https://www.ebay.com/itm/GM-15-x-7-S...53.m1438.l2649