The best advice on disassembling that gun is DON'T! I wouldn't bother to repair it.
If you choose to disregard that advice, DO NOT try to drive out the breech block pivot pin. It has a groove in it inside into which a plunger fits. If you try to drive it out, you will wedge the plunger and maybe break the frame.
You need to remove the lever first, driving that pin left to right, then try to make sure the plunger comes free. Then the bolt pivot pin can be removed.
Firing pin breakage is very common on those guns, and also breakage of the ejector trip. Another common problem is the ejector missing the cartridge rim due to poor fitting at the factory. (I may be wrong but I seem to recall that those guns were made in Germany, not by Ithaca, which always had a good reputation. Those guns hurt that reputation, no matter where they were made.)
As to converting that gun to something else, the breechblock is cast steel and the pivot pin is steel, but the sturdy-looking frame is a cheap zinc alloy. I wouldn't trust it too far. After a while, the pin will peen the frame and the fun begins.
Jim