Scooter, if I were to attempt a repair on a steel frame I would make a brass piece with the correct threads and install it before making the weld. It MIGHT keep the weld area clean enough to start the tap to clean it up.
Would I do it to someone else gun? NO
Would I ever really trust the repair? NO

I guess you could also bevel the crack install the barrel timed and weld it up, never to be disassembled.

Mostly would do it for my own curiosity. Steel K frames are the most apt to crack and they are just not worth it for what they cost. Sell the parts and move on.

I have made a lot of modern damascus for knives.I have a bunch of billets made up in the shop, but have been distracted lately with S&W revolvers.