In truth, probably the best plainsgame rifles are the 300 magnums, followed by the 270 and 30-06 etc...They cover the field of African plainsgame shooting very well indeed..But if you want to shoot the calibers you mention, then that is your choice, but be prepared to perhaps fail on ocassion..

I have hunted plainsgame with the .404 and .416 Rem. and it worked fine but I passed up some shots at some nice animals that I would have taken with a 300..This didn't bother me, but I have hunted plainsgame many many times. Someone on their first hunt might be shorting themselves by doing the same, but that is a personal decision that only you can make.

I am a great fan of the 9.3x62, but it is a fairly short range caliber..Your PH knows the country where he hunts better than any of us, I would suggest you take his advise.