Greetings gregrn43,
Another vote for one rifle each.
As for calibers, any of the 4 you have will do well.
For my 2 penny’s worth I’d bring the .30-06 and 180 grain A-Frame if you can find them AND if they shoot straight in your particular rifle.
Or, the .300 Winchester with 200 grain.
Also, the old and much misunderstood these days, Nosler partition is a very good “plains game” bullet.
I used a .300 H&H Mauser and 4x scope, with 180 gr NP, @ around 2850 FPS, during my very first time to Namibia, about 20 years ago.
It was in the rather flat geography, sparse foliage - more open conditions of Southern Namibia.
My two longest shots were a few meters past 400 and a couple @ plus or minus 300 meters.
My shortest shot was about 50 meters.
Most shots were around 150 - 200 meters.
Largest animals taken were zebra and Kudu.
The bullets performed perfectly, except very destructive on a steinbok @ about 50 paces.
At the end of the day, I could have done that entire Safari with a .30-06 or 7x57 just as well.
Your daughter will do fine with her .270 and 150 grain bullets or, her 7MM-08 with 160 grain.
Again the A-Frame is my recommendation if you can find them and they are accurate in her chosen rifle.
Otherwise I recommend the NP if you can’t find A-Frames and if her rifle shoots the NP accurately.
My hunting companion on that first safari used a .270 with 2-7x scope and 140 hr A-Frames with perfect success.
Another friend of mine’s wife used her 7MM-08 in South Africa with 4x Scope and Norma 160 gr “Oryx” bullet.
She enjoyed perfect success.
I have no experience with the Scirocco bullet but it has a very good reputation in Africa and elsewhere, especially where longer shots sometimes happen.
Practice much with shooting sticks from standing position.
I prefer the simplest 2 legged ones but some prefer 3 or 4 legged ones.
As long as you can get consistent hits with whatever type used, that is what matters.
I recommend scopes that are not overly powerful and not overly complicated.
For hoofed critter hunting I prefer a simple 4x for almost all (almost all) conditions.
But in open country like you will be hunting in, a 6x is a fine choice.
(I’m not very sophisticated but I can lift heavy things).
Waidmannsheil,
Velo Dog.