Success. Will post some pictures when I pick a new place to host them.

The large screw under the top lever was the problem child. I still out the head and pounded the remnant shaft to press out the trigger plate. Wood came off without damage.

Despite to amount of ancient rust and crud in this thing, the issue keeping it shut was the coupler. It had broken in half, and would effect the bolt when the top lever moved, but not enough to open the gun.

All that's been lost has been the top screw, coupler, coupler screw, and trip spring, so far. The firing pin bushings are covered in worse of it, and breach faces are eaten up. The barrel is done. The top rib could be fixed well enough, and the damascus is nice, but the bore are horribly cratered.