Preacherman,
I purposley asked this question because it is such a difficult proposition.
And I think my idea of a .416Rigby to be sound in that it provides a very happy medium between heavy gun and longer range capability.
The .404 an often forgotten yet highly capable round is in a modern loading every bit as capable as the .416.
Along your lines of thought the .458 Lott in a well made bolt gun with a nice low power variable with QD's would also fit the bill quite nicely. That round with a 400gr bullet is as flat shooting as a .375 and with a 500gr bullet it's a serious thumper.
Another round that may be of consideration but hasn't been mentioned would be a .450-400NE double with scope and qd's.
I don't know that I'd go with a .450NE or a 500NE in a bolt gun I would however consider the .450Rigby to be a serious contender. It's a nice round that produces serious energy with a .458 bullet at lower pressure than the lott and higher velocity for reach than the NE's.
As far as where we are hunting. Well lets expand the horizon just to complicate matters a bit.
10days in the Masai steps of Tanzania for buffalo + plains game and lion if possible.
10days in the Selous game reserve fro hippo, croc, leopard and another buffalo.
10days in the Northern Zambezi for sable, lion, leopard and eland.
Elephant, lechwe and situtanga in the Okavango. (Is situtanga even on license in Botswana?) I'd have to look.
Then we'll slip up to CAR or whatever it is called today for a Bongo.
And just to keep everything on the level we'll cruise down to Namibia for some springbok, kudu and gemsbok and if one presents it self a Kalihari lion or leopard hunted using San Bushmen trackers on the ground.
We'll finish off this grand adventure with some Nyala and waterbuck hunting in the Kwa Zulu Natal.
And of course we'd hunt everything from common grey diker and sunni up to Mastodon inbetween.
I hope that has unnarrowed the circumstances for you a bit.
H&H(must be serious geek to even think of such a thing) hunter