My HD shotgun doubles as my deer shotgun.
The reason I suggested possibly trading the full bbl. for either a deer bbl. or a bbl. threaded for chokes. At least you would get something out of the long bbl.
I've seen used,decent Mossy 500 slug and multi- choked bbls. for $50-$75 at more then a few LGS's.
Say you find one of each for $75, that's $150...now you've got $250 total invested. If they give ya a mere $40 trade-in for your long bbl, you've got $210 total in a gun you can use for HD and any kind of hunting you want.