Updated: May 9, 2020
Shot placement must be in front of the leg and not behind the leg:
All of them, including all Northern Hemisphere deer-species, the heart is in exactly the same place as this kudu:
Elk and mule deer that I have hunted or guided in Colorado have their hearts in exactly the same protected position.
The only anatomy difference is that they have lungs with substantially more capacity than Africa antelope because they need the supercharged oxygen for running at 8,000'-10,000 ft elevations.
That is also the reason why a lung shot causes them to lie down quicker than Africa antelope (not necessarily die quicker) - they are dependent on that 110% lung functionality for oxygen supply to the brain for 100% motor response.
Finally on Magnum cartridges: If that is the rifle the visitor shoots consistently the best, then that is the rifle he should bring to Africa. In the .30 Magnums use nothing lighter than 220 gr bullets and in the 7mms not lighter than 170 gr. The hunter will be well advised to keep a local truism in mind: "If anyone needs to shoot at game further than 300 yards then wild game are not in sufficient numbers to be hunted there". Where the visitor will ever be hunting any shot out to 250 yards will be the very high exception - most will be 40-150 yards.
Regarding the local favourite cartridge for both big and medium game and even small game: out to 300 yards a .308W and a 180 gr Federal Fusion bullet breaks both shoulders of all big game except a big eland and kills it right there.
A high lung shot or too far to the rear with a .338 Win Mag will not bring the animal down quicker than the same misplaced shot with a 7x57. Forget about "flat shooting" as shots are very rarely at 200 yards. 50-150 yards are the norm.
It is not the case size and geometry that kills the trophy animal but a well designed bullet - and where the hunter puts it on the animal.