I'm not going to say you did bad, but I think you could have made a better choice.
I know a fella that got one of the MkVs in .460 WM, back in the late 70s. Its a monster, and turned out to not be as satisfactory as he hoped.
I haven't looked much at this cartridge or Weatherbys lately, so if they have made improvements, so much the better.
The orignial Weatherby Mk V stock is a long way from the best shape to handle the heavy recoil of the .460. It will flat just hurt you more with that stock shape than the same round in a rifle of a different stock design. If your new Mk V has something other than the classic Weatherby stock, you will be better off when you shoot it.
Another thing is the cartridge itself. It is the big bad boy on paper, and in the field, however, back in the 70s, when I was looking at these things, it wasn't as well thought of in Africa as the .458 Win Mag. And this was for two basic reasons. One was the class of hunter that showed up with the .460 Wby, often someone who had bought the biggest gun, but didn't take the time effort and expense to learn how to use it. That doesn't sound like your plan, and good for you.
The other reason the .460 Wby wasn't at the top of the list of favorites was that, despite its huge power, there were numerous failures of the round in the usual hunting situations for dangerous game.
And the reason was, actually, the power of the round itself. The .460Wby is the fastest of the big rifles, launching the 500gr slug at almost 2700fps (as generally reported, velocities in reloading manuals top out around 2600 or just under). And it is that speed that gives problems.
Hunting elephants and cape buffalo are done at close range. Much of the time it involves head shots, especially when being charged. There is a velocity range, about 1900-2300fps where the big, round nosed solid bullets used in the heavy calibers will punch through the thick, rounded bone of the skulls and do the job.
Shooting these bullets significantly faster actually has given problems in the game fields, as the higher speed increases the odds of the bullet glancing off the skull, instead of penetrating. When this happens, even a perfect shot can be a total failure. Not a goood thing for the hunter, or his PH.
As I said, its been a few decades, and Weatherby might have corrected their flaws in the meantime, I just don't know. Sorry, I can't give you up to date info, but I assure you my out of date info is solid for the time it was current!
As to longer range (200yd), the .460 factory load shows a 3.3" mean trajectory for 200yds in one of my old books, so actually hitting at that distance is not as difficult as it would be for a big bore of lesser velocity.
I wouldn't go with a variable scope, a fixed power (and a low power at that) is likely to be more durable. $500 or even $1000 saved on a scope is wasted if it packs it in after the 19th shot. Strong, solid mounts are needed. Anything less is false economy.
Good Iron sights are a must. The Mk V I know didn't come with any sights. Does yours? Everything can, and will go wrong, even good scopes can be "offline" when you need them badly. Hunting things that hunt you back means having simple, rugged, fast to use sights available at an instant's notice. Many folks won't use anything else.
I have a little experience with the .458 Win (although only in the US
), and most of my shooting it is with cast bullets at approx .45-90/.45-120 power levels. The elephant/cape buffalo loads are not for me, other than to say I've done it.
Now, I haven't said all this to tell you that your going to regret your choice, I hope you don't. I just wanted you to be aware of some things, before you leave for the Dark Continent. I envy you that, because its a trip I'm never going to make. Please keep us updated and informed on how this goes. Pics of the rifle would be nice, too. I'd like to see how it compares to the one I knew nearly 40 years ago.
Good luck, and good hunting!