They may be adequate for the animals that you may be hunting and then again the guide service that you are going to use may not allow them. The best thing to do is to contact the guide service that you plan on using and ask them about it.
I know that here in North America there are guides for moose and bear in Alaska that require a minimum of a .30 caliber and up.
They would be adequate for the smaller of the plains game, but if you're planning on getting into the kudu and eland size animals, you will want to move up to at least a good 30 caliber or better rifle with a good bonded bullet. As critter mentioned, when you pick out a PH to go with, it would be a good idea to get their recommendation to make sure when you get there that they don't say your rifle is too light for the task and make you use an unfamiliar one of theirs,
Over the years I have seen several elk and deer hides left in the woods by hunters and I have to wonder why they do this? I fully understand and agree about getting the hide off the animal as soon as possible to cool the meat, but why not pack out the hide with you and use it? As far as I know there are no state laws that require you to take the hide home, but to me why waste such a beautiful part of the animal? Some might think they have no use for the hide or it costs too much to tan....