How long is your hunt? If you are going for seven days, forget a second barrel because you are likely going to spend most of your time looking for a buffalo. At ten days, if your DG choice is a 40 something, then a dedicated PG barrel begins to make sense. Or you can solve that conundrum, by forgetting the 40 something and get a .375 in spite of your 9.3 (at last count I think I have three of each).
I have 6.5x55, 257 Wby, 300 Win Mag, 375 H&H, and .404 barrels for my R8s. Thus far, when I travel to Africa with a R8, only the .375 has come along with me and that includes a couple of two-week expeditions. It is just such a perfect choice and has killed every buffalo (or anything else I have pointed it at) quite conclusively.
I shoot all my scopes both eyes open, it is easy to train your dominate eye to do so. However, with respect to scope power, a 1 or 2 x whatever will handle any opportunity in Africa. When hunting plains game, I keep whatever scope I have dialed at 4X and do not remember ever cranking one to a higher magnification there.
Finally, If you do talk yourself into a .416, and you are hunting more than seven days, then, as suggested above, get a .300 Win Mag with which to marry it. While hunting buffalo, you will primarily be hunting buffalo and likely in an area with fairly limited PG. If the kudu of your lifetime does pop up just shoot him with the .416. In Zim in particular, the range is more likely to be under 100 than over 200. Convert to the .300 when you have your buffalo.
I have never used solids for back up. 300 or 400 gr A-Frames do just fine on buffalo coming or going. Most PHs will now tell you that as well. I always do bring a few solids, but they are for any members of the tiny ten we might encounter. I would not consider bringing a .243 to Africa even if the bullets were constructed of unobtanium. I have never attempted to shoot a member of the tiny ten with a 40 something.
So if my calculations are correct, you can either buy one barrel - a .375 or two barrels - .416 and .300.