The repair will probably involve cutting the barrels back of the bulges, then re-installing the front sight and solder back the rib. So far, any quality gunsmith can do that.
Now the tougher work...
Have Briley chokes installed in both barrels, and have someone like Lee LeBas (learmes
msn.com)or JJ Perodeau at Champlin (
www.champlinarms.com) do the work to install the sight, solder the rib, and re-regulate the barrels.
It's going to cost plenty.