Along with my original suggestion, if the shanks of the screws are a bit snug in the body holes and the screw heads are completely gone, I would use a parallel punch, or a suitable gauge nail (4"?) with the point ground off flat, to "drift" the screws thru tapping with a hammer. Obviously care required and I'd alternate between the 2 busted screws to even out the movement. I'd think that'd get it moving, and when you've got a gap between neck and pocket you could use gentle leverage with something suitable.
I'd obviously remove everything else from the body, scratchplate, electrics etc, first so you've got nothing to get damaged.