pocketrocket,
I bought a huge 3 jaw puller (from a discount tool place) to pull the drums off a car that sat for around 15 year that I was restoring.
Just take the spindle nut off, soak the stub axel in penetrating oil for a few days and use the puller to get the drums off. Whatever you do, DON"T STAND IN FRONT OF THE DRUM!
I've had one come off and shoot across the garage and leave an impact crater in the opposite wall of the garage!
This is a better solution than cutting up you backing plates and pounding on the back side of the drums with a hammer.
Worked for me anyway.
Cheers,
Doug