What's your plan for the action? If for a custom, I'd let my chosen smith take a look at it and fix it. Could be an easy fix. Maybe somebody here has already seen something similar.
If not for a custom, I'd be tempted to try to run a 1/4-28 tap through it and use a long action screw from Brownell's and cut it to length. Looks to still be plenty of thread left.
