Albert,
Start by getting a hold of some gun shops in Alaska. Like others have said, in most if the US a .375 is a "keep the dream alive" safe queen. Some friends of mine traveled to Alaska for a roll your own caribou hunt last year. In the big state we found .375 rifles in all states of repair or disrepair at many gun shops. Grizz and Moose hunters alike carry them, in addition to folks who carry medium bores as insurance against bear. Ping some of the Alaskan based members and maybe they can hook you up with a local gunshop that deals more extensively in medium bores. Someone has a beater laying around. I was in close to the same boat as you whence planning my safari. Whitworth, Winchester, and CZ rifles were the best bargains for a fully functional bolt .375 at the time (2014). All of these were in the arena of $1000 give or take a hundred or two for a ready to go rifle. You may have a hard time finding anything for under $600 unless you can get into an area that has high use for these medium bore rifles (Alaska or Africa) and thus a higher amount and variability of stock. Good luck on your project, and good luck on your safari!
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