If the crack is flexing under pressure (highly likely), then the case is allowed to expand more than normal and may not contract back to normal size after firing. Check the metal head of the case just in front of the rim with a good caliper.

I'd be thinking of having the chmber bored, TIG welded, and chamber sleeved.

Now, that does not account for issues in the uncracked chamber. Better check that one, too. Carefully!!