A. With 75% lining left on the shoes and the stroke at 1.25”, I question whether the drum is within spec or the s-cam bushings are worn out. With the wheels jacked up in its current state, check to see if the wheel will rotate in the forward direction with the park brake released. This confirms whether the s-cam bushing are worn or not.
What is the pressure being used to get the 1.25” stroke measurement?
Using a pry bar the adjuster should only move 1/2”. If it goes beyond that it is an indication that you have foundation component issues.
I am thinking that the reason why the brakes lockup backing up is because of reverse cam rotation. With a bad s-cam bushing with reverse cam rotation the top shoe becomes the lead shoe and because there is too much clearance between the shoe and drum, the cam block locks in the drum.