Thanks to all of you for your suggestions on how to remove an epoxied in reduction sleeve that wasn't quite bottomed out in the existing bore. Cannonmn gets bragging rights for the winning solution. I've never been a fan of Harbor Freight tools, but in this case one of their 20 buck weed burners did the trick. Supported the barrel as best I could on some cinderblocks and tried to heat it fairly evenly. Once I saw a puff of smoke from the original vent hole I was pretty sure the epoxy was melted or nearly so. There was just enough liner beyond the muzzle to get a pipe wrench on it... at first it wouldn't budge but after another 5 minutes or so heating it finally started to turn. That is when I knew for sure that one way or another it would come out. Managed to get it backed out another inch or so by twisting it with the pipe wrench then suspended it by the breech end. A 12' stepladder with a block and tackle served the purpose. Heated the barrel just a little more and gravity did the rest.
Will get everything cleaned up and then put it back in probably on Sunday. This time though I think that I will shove it home and then weld it in place at the muzzle.
Again, thanks to all of your for your most appreciated suggestions.