repair cracks in the stock?

Old dry wood.
Soak and clean the affected area with acetone to wick any oil from the wood.
Use a clamp and a couple scrap peices of wood or leather so as not to mark the stock, clamp it to see if it will squeeze together. If so remove clamp and use slow cure epoxy in the crack and clamp allow to fully cure before removing clamp.
Dont use 5 minute stuff it cures too quickly, not enough time to soak in.
Once you're done clean the stocks and give it a good drink of boiled oil to refresh the wood.
Good luck.
The old way would be to use threaded brass wire drill a hole smaller then the wire diameter, apply old school hot pot glue squeeze the affected area together screw in the wire trim and refinish wood as required.

there are those working wonders on way worse than this one , you will get it fixed , just be careful and do it right ,