Ended up having to remove both rear drums. Cut 4 pieces of 1/4" flat steel bar, beat them in 90 degrees apart behind the shoes, and BFH'ed the drums til they popped right off.
Ended up finding the 3/4 ton rear wheel cylinders at autozone for $40 a piece.
Now my next dilemma- where on earth do I buy a set of rear brake shoes for this thing?!