Would a barrel off a RH model 70 in 416 Rem fit a LH action in 375?

If you mean an M70 Classic, then no.
The barrel has an extractor cut that is on the right side of the breech for a RH action, and on the left side for the LH action.

If it is a .375 H&H barrel there is enough shank to cut off the threads and rethread and redo the extractor cut. You will end up with a 23" barrel instead of a 24" barrel, a shorter shank (or "Knox form"), but you could rechamber then to the spiffy .375 Wby or .375 Ruger or even the .375 RUM.

You could do the same with a .416 Remington.
Cut off the threads and rechamber to same .416 Remington, or .416 Ruger, or .416 Dakota ... with 23" barrel.

This would be cheaper than buying a new barrel and installing sights and recoil lug on the barrel.

Is the transplant barrel worth the effort?
Or should you find a new barrel fresh as the driven snow?
That is the question. Consult your transplant surgeon and the donor of the barrel. Some of those Winchester barrels are rough and oversize and would not be worth it. Lemons happen occasionally even from the "Custom Shop" on a .470 Capstick Big Five.

thanks for that thoughtful response RIP!

Good on 'ya!

Rich
DRSS