The difference in shoe width is made up with a deeper dish in the center of the backing plates for the 2 1/2" brakes. Overall axle width shouldn't change, it's still axle flange to axle flange. You will need stock length A body axles with the 4 1/2" bolt pattern, 10X2 1/2" backing plates, drums to match ('72 Charger is what I used), wheel cylinders, hardware, and shoes. Make sure you get the E brake levers and the spreader bars from the donor car since they are made of unobtainium. I used the 10 inch brakes because the parts are cheaper than the 11s, I wanted to keep the 14" wheels, and there are a lot more donor cars available. You can find them under '66-'79 B bodies, '70-'74 E bodies, F,M,J bodies (Volare, Aspen, Dippy, 5th Avenue) and even '73-'76 A bodies with 4 1/2" bolt pattern. In my opinion early A's don't need 11" brakes because they are so light. With 10X2 1/2" rear brakes and '75 A body front discs, my '66 Valiant will stop on a dime and give 8 cents change. Don't know for sure that you will need 15" wheels to clear the 11" brakes, but everything I've ever seen with those brakes had 15" wheels. Hope this helps.
