OP- You have a lot of good input here, and I hope it all works out for you. If there is any way for you to still go, you should definitely do it. You won't regret it. If you want a couple good outfitters in that I've used in RSA I can sent you links to them.
The shooting is longer than you may expect, I was often taking 200-300 yards shots, sometimes 400-ish on Kudu or Gemsbok.
Kudu aren't especially tough, so a well constructed bullet out of a .270 win is adequate for that species.
For Gemsbok,Waterbuck, or Zebra, 30-06 or any of the .300 mags are fine. I prefer using lighter, thus flatter shooting nosler paritions.
I used a .270 on Kudu, Blesbuck, Bushbuck, Warthog, Blesbuck, springbuck, impala, and smaller stuff like duiker and stienbuck, I was not under-gunned.
I used .300 Win Mag on Gemsbuck,Kudu, Blesbuck, Black and Blue Wildebeast, Impala, Hartebeest & Springbok.
30-06 (Supressed) on a warthog
.300 wby mag on some of the larger stuff listed above, plus Nyala.
I took a Waterbuck and a couple other things with a .340 Wby mag.
I'd recommend a 3-9 variable in a decent quality optic.
You may end up having to take a 30 yard shot, so being able to think quick and adjust to low power quickly is an asset.
Get a good comfortable sling, comfortable walking boots. Practice from shooting sticks and learn how to use them, they are a great tool.
Good luck.