It is a European 375, actual bore is .366. If a guy has an itch he should scratch it but personally I would build a 375 Ruger or 375 H&H just because brass and bullets are much easier to come buy, as is loaded ammo if you don't reload. That said, I have a few guns that aren't easy to find brass for so I don't even take my own advice.
There are a few rifles chambered in that cartridge, including Sako, probably be much farther ahead just buying one of those and selling the Sako. Other choice is to by a 9.3x62 and just ream the chamber to 64. Rest of the stuff including the feed rails will be correct and work right with no futzing around. Post pictures of the build when you get it done.