Sounds like what we in the UK refer to as a rebraze lump. Not a simple job I'm afraid . The barrels need to be taken completely apart ,all the old brass/silver solder cleaned off ,rebrazed the ribs relayed and blacked . That's the simple part . Bear in mind the original the barrels would have been brazed together then machined ready for jointing the barrel into the action body . When re brazing no matter how careful you are there is no guarantee that every thing will go back together precisely so that the barrel may not fit the action as it did before . It is down to the skill of whom ever does the re jointing to get it as close as possible . Over all and speaking from the experience of having done a fair few of these it is not a job to be taken on by some one who has had no previous experience and I will only take such a job on, on the understanding the the out come may not be perfect . You do not have proof to contend with but even so if the barrels are not in reasonable condition I would consider the gun to be beyond reasonable repair .
