I will take the bait and attempt to answer based on my experiences..

The closest and most similar example I might have is my first trip to Zim...brought a 300RUM and a 416Rem..was suppose to be a buffalo/leopard hunt along with plains game for baiting, etc...I had unfortunately loaded 180Gr Nosler Accubonds in the 300RUM..velocity was checked at 3370fps..after the bullet failing miserably on a waterbuck and kudu..switched to using only the .416 for the next 16 days of hunting..shot numerous impala, another kudu, 2 zebra, eland, wildabeast, 2 bushbuck, etc..most shots were 150yds or less..however did shoot one bushbuck at a ranged 265..fortunately made the shot..

My velocities were around 2450fps using a 400gr Swift A-Frame bullet..my bc might be a bit better however you have a few more fps..

I personally feel, as you state, there are better choices, or you could bring 2 rifles which is what I always do anyway when traveling that far..things happen, scopes go bad, rifles break, etc..however if your heart is set on taking the 458 Lott, believe you could be fine out to 250-275..after that its going to get a bit more tricky...IMHO..

I took a .375H&H to Cameroon last year..great flat shooting caliber..worked great on PG..however was a bit disappointed on how it performed on the western cape buffalo...even though it was a good solid shot and a one shot kill..the initial result was very noticeable compared to the others I have taken with my .416...for DG, think you choice of the .458 is much better than the .375..

As one of the other members has stated numerous times, its more the man behind the gun than the rifle or caliber.. practice.. the only reason i was able to make shots with the 416 beyond 200yds is that I did practice and knew where to hold on the scope at 250..othewise I probably would have blown the shot..

My .02's ...get what you pay for.

Ripp