Superglue and the usually available epoxy choices are not good choices if you might plan to pour a nosecap. The epoxy turns into a stinky mess with that much heat, and the superglue melts then burns (it is not a cyanide problem but it will irritate your sinuses!).
I'd be tempted to treat the cracks a bit like woodwind music instrument repairs. Carefully drill and cross-pin at several locations to hold it together. The pins can be metal, threaded into the wood even, with wood caps at the surface which match the grain.
Or you could inlet a narrow cross channel at intervals in the barrel channel, and glue pieces of wood to hold it together securely. That's probably much easier and won't show on the assembled rifle since nothing reaches a visible surface.
Do I racall correctly that the new cast lock plate for that lock is slightly larger, enough to not fit the original inletting? I doubt it is enough larger, but perhaps Jim could answer?
Gerald