I know this is going to be a little strange to see here, but I didn't see any where else where it might be a reasonable fit, Mods move it if you are so inclined. I'm not in any way connected with http://fairfaxfirearmsrepair.com
This guy makes revolving rifles using revolvers as the action adding a stock and forearm and installing a longer barrel.
It looks like really nice workmanship. I never knew he existed but I'm going to take some work to him. It's nice that he isn't but about 25 miles from here.