RE: My gun for Africa....
A few of my pheasant hunters go to Africa every year on a Safari before coming to my place to hunt. They shoot all plains game normally, and they all shoot 7mm Rem Mags or 300 RUMs. They've never had a problem with wounding/losing any animals with those calibers.
If you are going to be hunting the dangerous stuff, I'd go for a 375 H&H myself. I've shot one a number of times and it was surprisingly easy on my shoulder. I'd compare the recoil to a 45/70 with more of a jolt than a slower push. The gun I shot in 375 was a Ruger #1.