Is there a relatively pain free way to Rechamber this into a more commercially available cartridge? Or just sell it and start over. TIA.

How much pain is free? You pull the barrel, set it up in the lathe, and chamber as normal. Then put the barrel back on.
There is nothing wrong with the Norma, if you reload.
I would move up to a larger caliber though; no use for a 30.

Yea, its called reloading . The Norma is the same thing as a 30-338, dies and brass are easy to get. Personally I would take that over a Win Mag in a heartbeat.

Not the same as a 30-338 but it is a fine cartridge. I think it is the best of the .30 magnums. The 30-338 is very slightly smaller but the different is very slight. Regards, Bill

300 winmag would be the easiest
300 weatherby would be a bit of work
300 rum would be more