If you want to use a .375 Ruger... Go for it! It sounds like the “classic “ looking African model is your rifle. I have a .416 Ruger Alaskan, which is basically the Guide Gun. I prefer the short barrel. In fact I took all of the animals you listed, except the blesbok, with it. The .375 would be great for all the animals you describe and when you go back for your DG hunt, you’re all set. Just keep in mind the .375 kicks twice as hard as a .30/06 and the ‘06 will easily take all of the game you list. Just put a good bullet in the right place. Me... I’d go with my gut and take my dream rifle.