47-55.1 Unexpected disk brake - wheel problem

[TX3100Guy]

A month or so ago, I installed four disk brakes on my 1953 Chevy truck. The manufacturer of the rotors/calipers claimed that they worked with 15 inch wheels. I also purchased a set of chrome "Smoothie" wheels from US Wheels and installed them after the brakes were already done and on the old wheels.

While working on my leaf springs, I tried to rotate one of the rear wheels when the rear axle was off the ground. I found the rear wheels unable to rotate. Removal of the wheel/tire proved that the rotors and axle were able to rotate on their own. Further investigation showed that the wheels contacts the outer edge of the caliper, preventing it from rotating.

The chrome wheels are 15 inch by 6 inch wheels with an offset of 6 and backspace of 3.75. In contacting the brake manufacturer, they indicate that they designed the rotor/caliper to works with "factory stock wheels". which is not what I currently have.

Interestingly, the front wheels/tires have no issue with rotating. Which means at a minimum I'm stuck with two brand new wheels and new tires that don't work properly with the rear brakes. Even more confounding is, I don't know what size or backspace of wheel to use on the rears now. Any helpful suggestions will be appreciated.