[ford38v8]

You don;t need a hokey jury rig notched board. The parking brake operates the cross shaft just like the foot pedal does. Use the parking brake one notch at a time till you discover the sweet spot for each wheel. Make your adjustments to coincide the wheels, with the rears a couple clicks behind the fronts. Front or back on jack stands only? Put all wheels up, do it all at once. Road test is absolutely required, no matter how close you think they are adjusted, one wheel or another will need another tweek.
For those who can't get all 4 to do the same every time, your system has seen better days, and needs rebuilding like all other things mechanical. New cables, properly lubricated, and perhaps most important, at least for me, is floaters. These little gems convert the Hotchkiss adjustment system to the Bendix adjustment system, which uses a brake spoon to adjust the stars. This single modification allows the shoes to self-energize like Ford had advertised back then, and does it with zero interference of wedges that tend to hang up due to the constant pressure and friction against those Hotchkiss adjusters.