I would put a single rod through the wrist. I wouldn't use all-thread rod, but a 3/8" rat tailed file. Most modern rat-tailed files are case hardened and not through-hardened so they don't require annealing, and with a hard case and soft core they are extremely rigid.
The trick to making the epoxy (I would use Acra-Glas gel, nothing else, too many reasons why to list here) get where you need it to is a vent hole. I would drill the hole from the center of the breech plug behind the tang, under the tang and all the way down just to the rear trigger guard tab and drill a small (1/8") vent hole down through the tab to intersect the rod hole. 12" drills are available at most home stores, where you buy an un-handled rat-tail file. Chop the tang end off of the file and use the rest if it isn't too long, terminate it just behind the tang screw hole. Plug the tang screw holes with clay or match sticks wrapped in masking tape so they don't get completely filled with epoxy. Use a smaller dowel to drizzle and butter up the entire hole, coat the file, and slowly insert the file into the hole until it bottoms out. Fill the hole up to the surface with Acra-Glas and plug the vent hole so the epoxy doesn't run out. You will also want to clean out the excess from the trigger guard tab hole or it will have to be re-inlet. Shave back the epoxy so the barrel fits again, clean up the mess, and you're done.