I believe Montana Rifle Co now makes them.In CRF the reasonably priced option are more or less limited to the Zastava M70. CZ and Win M70 Classic are getting harder to find.
that winchester is rightyZastava: https://www.gunbroker.com/item/800761746
Browning A-bolt: https://www.gunbroker.com/item/803140972
Winchester: https://www.gunbroker.com/item/798327267
that winchester is righty
A reasonable concern about the 375 Ruger. But since it's creation it has not gone away or been sidelined, quite the opposite. Ruger is still making both right and left handed rifles in it and now so is Savage and Mossberg in right-handed. As for ammo, besides Hornady, Swift is now making rounds for it. There may be others.375 Ruger in left hand is widely available, concern that finding ammo could be a problem in some situations down the road.
First choice still remains the 375 H&H but 375 Ruger may be the answer if all else fails.