I did my Rr Pking brake shoes last year , 93 J30 , and I noted if the "actuator" - like a small lever/cam that expands the shoes can be sort of reversed and causing the shoes to be a slightly bigger overall diameter than would be able to go back into the Drum/disc assy. It is beyond me to illustrate really here , ah , I just know I saw that looking like a real problem and took a photo of the other side before attempting disassembly on it. Next is the spring and adjuster , you know ya got to adjust down further for the added thickness of new shoes - other than that the only thing I noticed as a remote possibility is if the shoes get "flattened" out in the backing plate channel due to the heavy hold-down sprigs , THAT will bloat them way out giving a NO-FIT.
One thing I made sure of was to do a "side by side" of the old part next to the new ones , whilst also
making sure a Rt and a Lft shoe for ea. side with an exact match , radius , chamfers, pivot ,etc.
Lastly ,very remote , but if some kind of tension developed subsequently in the E-brake cabling that "fools" you - giving action. Like the actuating lever/cam is torquing out and "applying the shoes"