Re: Help determining value
Rethreading the barrel from a Mauser to a Rem 700 isn't very practical since they each have a different thread pitch.
Unless.... you happen to have a long enough breech to cut off the entire thread tenon (which isn't very long on a Mauser).
Then, you can recut the tenon, re-thread, and re-chamber to fit your 700 precisely.
Of course, 23" is on already the short side for a 300 WM.
Even so, you'll likely need to rebarrel the Mauser for it to sell well. So, you might not save much unless it was an exceptional barrel. And, if you already know that to be the case, then I'd leave it as a sub-MOA Mauser.