verify the pressure is the same is the first step.
prove that then you can dig further, otherwise you are just guessing.
If you do not want to do the above
Did you move the drums with the shoes ???
One could also move the backing plates side to side ( except for the ebrake cables being hooked up)
.
You appear to have done everything but the pressure test and the backing plate swap. So I might just consider swapping the entire assemblies side to side.
A long shot but make sure the RE bushings , spring mounts U bolts etc. are all in good consition. I had one several years back that had a brake pull to the right. It had been to several shops and the customer wanted disc brakes. When the car came in the front cross-member was rotted 3/4 of the way around on the right side. I had him drive 60 miles to see it for himself. It was baltantly obvious yet 4 or 5 shops did not see it. You might need someone else to take a look at it.
