Nick, these days new doesn't mean the drums are correct or that they are even made correctly. Same goes for shoes.
I purchased AC Delco drums for another vehicle and had to have 1/4" of meat machined off of the outboard side of friction surface of the drum. The shoes were pressed up against "the curb" and wouldn't move.
In your third picture, it was the ridge where the friction surface meats the mounting surface.
I guess you don't have any old parts?
Make sure the shoes are resting on the raised bosses on the backing plate and not down in the recessed area.
Did the wheels roll freely when you first got the truck?
Are you having the same issue on both sides? We're looking at the driver side. See if the passenger side drum will fir on this side.
