For a repair like that, i would use titebond 3. Titebond 2 would probably work too, and needs clamped less long. Also, i would practice putting the piece in place, and holding it with a clamp of some kind. Maybe rubber tubing or cable tie would work better than a clamp. Leave it clamped overnight. Also, as suggested by Wayspr, be sure the tang isn't what caused the piece to break off in the first place. Epoxy isn't needed for this repair, and would be messy if i used it. The squeeze out from a waterproof wood glue is easier to remove than the mess epoxy would leave. Wood glue squeeze out can be readily removed after an hour, and can even be removed nearly right away with a damp rag.
Properly done this repair is permanent, and a new stock won't be needed.