problem with 15" steel wheels

Approx 3 months ago I purchased a set of small bolt pattern 15 x 7" steel wheels with 4.25" back spacing for my 72 dart from a place on ebay that takes original small bolt steel wheel center sections and puts them on new 15" outer steel wheels. When I finally got around to painting them and getting new BFG T/A's mounted I found that the front wheels are rubbing on the calipers and will not mount. The rear tires are mounted and look great but the fronts will not clear the calipers. I compared my stock 14 x 4.5" steel wheels to the new 15" wheels and found that the outer wheel that they used is different than the stock wheels. When you look at the back of the stock wheels you can see the angle of the second step (transition) has a different angle than the new wheels. Has anyone ever had any problems like this?. It appears if the back spacing was either 3.75 inch or 4.00 inch it would give enough clearance for the caliper. Do you think that I would have any clearance issues if I had someone change the back space on the new wheels to a smaller back space?. Any help would be greatly appreciated. Or could I get away with trying to find .25 inch wheel spacers and using longer wheel studs. Thanks again.