I would jig it up and use a mill or a carefully indexed drill press.

To me it looks broken all the way across. Through on both sides.

I guess, depending on if you were a buyer or a seller, what to do about the obvious cracks and what they really represent, is a matter of opinion.

I wouldn’t think favorably upon a person that sold me a shotgun with a stock that was broken clear through that he had hid the crack with superglue until he had my money.
But that’s just me.

Out there doing it best I can.