Brian, my 1877 Lifter 12 gauge had pitted bores. I mean PITTED! Brad Bachelder removed a ringed bulge, relaid the top rib and honed the bores. The 'Plain Twist' barrels really looked nice after Brad restored them. When he was done, the bores measured .755" with .104" wall thickness at 14" from the breech. I had him come up with a happy medium....remove as much of the pitting as possible, but don't leave me with a scary wall thickness! I shot my share of Polywad Vintagers in those barrels with no issues.
http://parkerguns.org/forums/showthread.php?t=2044