A second issues is encountered when the later '65-'66 F100 self adjuster hardware is installed. The stock '53-'56 brake shoe retainer clip is too thick to put both springs and adjuster cable on the top pin. The thickness measured 0.240" and needed to be reduced to at least 0.130".
None the less, I still was able to use the magnetic base and grind them done with a 4 1/2" angle grinder.
The next issue was that on the drive's side, the adjuster slot was in the wrong place. It appeared that the backing plates are the same stamping from side to side and that the clocking of the mounting holes is what determines the mounting direction. They also used the same adjuster originally from side to side. With the addition of the self energizing hardware, there are specific adjusters for each side.
With a little bit of machining, it was ready to go.
And here you have it...'53-'56 Ford F100 backing plates on '40 Ford spindles with '65-'66 Ford F100 self adjusters. All that is left is the bearings, drums and brake lines...