Slot Mag Question

Those look great Turbo44Dart! I have a question for the group, slightly different, but not worth starting another thread. I found these 14" rims local that I believe are 6" wide, seller is verifying. Although it's not a 15" rim like I'd prefer, it would allow me to run the 215/75/14 tire size I prefer in front. Seller say's there a GM bolt pattern, but I thought these uni-lug could fit either a 4.5" or 4.75" by flipping the washer to the desired size. I've posted a picture of the back of the rim. I do have the BBP 4.5" hubs, will these work. He only is asking $50 a rim.
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