I would remove the lock, stand the gun on it's butt put painters tape over the crack tightly and fill the crack from the lock mortise with superglue until it won't hold anymore and let it set up. Remove the tape, you might have scrape off a little glue residue and add a touch more finish.
Next I would relieve a little wood from the lock mortis where the back of the lock sits.
I had a TC lock that I had to knock out from the opposite side, it was TIGHT. I used one of those finger nail emery boards, cut the end square and ran it around the inlet until the lock would fall out on it's own and still have no gaps.
I ended up with this fit.
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