Also not sure what you mean by "80% finished." If you mean unblued or unengraved, you should be able to find something. If you mean missing some of the necessary machining to make it function, well that would be a rare bird probably found only in a gun manufacturers scrap dumpster!
It isn't hard to find a Thompson Center "Contender" single shot action alone, although they would normally be "100% finished" and are more like the H&R mechanically (has a hammer) than the 219.
A TCR '83 or '87 action is a little more like a 219 mechanically (hammerless) but would be much harder to find than a Contender. And you normally don't find them as actions alone. The TCR also came with 12 guage shotgun barrels somewhat like the 219 "combinations;" the Contender only came with smallbore shotgun barrels (.410 and 28 guage) because the frame is too narrow for larger shotgun barrels.
