I have a couple of questions...
What are your rifle options other than the 358WM, or is that your only choice?
30-06, 300WM or other .30 caliber will sort you out for all the antelope, although I would suggest something bigger for Eland.
What are you "planning" on hunting?
Is Buffalo possibly on the menu?
Understand that things don't always go to plan and if you want to hunt Buffalo, you will be SOL.
If you are possibly looking at Buffalo, go with a 375 caliber of your choice.
It's the most versatile caliber for hunting Africa.
I'm partial to the 375H&H for ammo availability but I doubt any of the animals will notice if you used a 375Ruger or Weatherby.