My personal view, based on more reading and conversations with PHs, rather than lots of experience in Africa is that you would be better to go bigger, with something around 8 x 64s, 338-06, .318WR .333 Jeffrey, 8.5x55 or perhaps even a 9.3 x 62 or an 8x68 or 300 or 338 win mag. This depends were you are located though.
I had a long conversation with my firearms licencing officer about these calibres and was told in no uncertain terms that none of these would be allowed for UK use, so the only option for me would be a 30-06, which is why I have a 30-06 and a 375 H and H for UK use and plains game.
If I lived elsewhere or our rules changed, I think I would swap them both for something in-between.