Safarihunter and Shakey.
I friend of mine, came first time to Africa with me, last year in November. He asked the same question as so many of us has done several times.... What caliber... Now, this is my recommendations... HH 375 is more then enough for all games on earth. We, the hunter, dont really need "stoppers", we need quick and good kill at first shot. The important thing is, of cause, were you hit animal, but also what you use for ammunition. The most important for choosing rifle and caliber is that you like what you use, that you really look forward to shoot another shot, that you know that were I aim, there is were I will find entrance of bullet ! HH375 good enough for everything. Anything "bigger" just for fun, if you can handle it.
BTW, my good friend Anders, bought him self a Blaser with some different barrels, incl a double HH375 !
Stay safe and God bless.
Michael