Shortstroke,
You should be fine with those specs. Are you planning on shooting zebra or wildebeest? Those would be the only 2 animals that I would worry about, as they are INCREDIBLY tough!
But IMO and from my experience, you're better off with a well placed shot out of a 40lb bow than a badly placed shot out of a 70lb bow. Are you planning on shooting anything bigger than a kudu or wildebeest? The only advice I can give you is that you ensure your bow is well tuned, that you have practiced ecstensively, and that you set yourself comfortable limits, that you are consistently accurate at, and stick to!
Also, if you're hunting out of a hide, built yourself a "hide window" to practice out of I made one a few years ago out of plyboard). Shoot at many different distances thru the window and make sure your distance perception is accurate thru the window. Find out from your PH if the hides have camo netting on them. If they do, ask him if it would be possible to remove them if you don't want to shoot thru them, if not, then ensure that you practice shooting thru the same netting. I wish you luck and hope you enjoy it! Make sure you tell us about your trip!
I hope this has helped!
Nigel