1st, disconnect the E brake cable upstream. Saturate with penitraiting fluid. Can you spin the drums?
Now try losening with a 5lb hammer to move the drums, if no, add fluid
Then 2, remove the brake lines and unbolt the cylinders.
Now try losening with a 5lb hammer to move the drums, if no, add fluid
3 ideas;
A) saturate everything inside with penitraiting fluid+5lb
B) heat the center of the drum (just one spot) until you can't heat it any more, then 5lb. Repeat fluid.
C) canned air to the wheel bolts (freezes them), then hammer to drum. Repeat fluid
All you need is a little movement and that drum can be pounded off. If it's already moving a little, then it will need to be pounded off, 1mm at a time
I went through this exact same process this last fall. In the end I was trying to heat the entire drum, when I stopped doing that and only heated one little quarter dollar sized spot, then the 5lb, that is when it finally moved, a very tiny bit.
After that, I heated each spot of the 5 spots, between the lug nut bolts, then it was loose enough to pound off. It still fought me but it came of a thread at a time.