Morga - the 240gr W-W is a fine bullet. I've looked over the species you're interested in taking: "Eland, Kudu up to 54 inches, Nyala, and Limpopo Bushbuck" and I'd like to offer up a little advice to consider.
The Limpopo Bushbuck is about the size of big southern US whitetail deer. 120-150lbs max. They are only about 12" or so thick trough the shoulders.
The Nyala is NOT as big as they seem in photos. They have very long hair along the underside of their belly that make them appear to have a bigger body than they do. They are actually about the size of norther US whitetail and run 225-300lbs or so. They are at max 18" through the shoulders. Side note: because of the long belly hair the biggest mistake made is to aim too LOW on the shoulder.
A kudu is about the same body size an American elk but they are not as think through the shoulders and they don't have the longer/thicker hair on their bodies as elk do and they don't wallow in mud. My wife describes them as being "elegant". Good bulls will go 600-700lbs or so and be around 24" through the shoulders.
Eland are big and heavy but they are not as thick through the shoulders as you would think. They do have heavy necks and heavy hind quarters but through the shoulders in the vital triangle not so much. Maybe 30" give or take.
I my opinion a 180gr mono metal bullet (TSX and NOT the TTSX) will work marvelously for you. In the bushbuck, nyala and kudu they will leave small entry and exit holes and little damage to the hides. Very important for your flat skin rugs or mounts. On the eland, that bullet in just a 308W will very likely pass through if you're inside 150m.
In general, all African antelope species are thinner across or through the bodies due in part to the high summer temps. Harder to keep a think body cool whereas deer, elk/stag species in the colder latitudes, thicker bodies help retain heat in the winters.
The reason I recommend the TSX over the TTSX is the rate of expansion is higher in the TTSX and they don't drive as deep.
Next benefit is there will be a good bit less recoil and they will be much flatter shooting. If you zero for a point blank range of 150m, at 100m you'll be about 1-1 1/2" high, dead on at 150m and 1-1 1/2" low at 200. The vital triangle on the smallest species your after, the bushbuck, is about a 4"circle. Means out to 200m all you've got to do is put the cross hairs in the vital triangle and squeeze. No guess work.
My last thought are these. While I don't know what part of RSA you're going to but, I do know that the species your after are all "bushweld" species and not open savanna. The limpopo bushbuck and nyala are actually more "riverine" and thick cover. Similar with the kudu being a "browser" and not a "grazer" they will be in the mopane/acacia treed areas. Eland are "combo" feeders, browes and graze. My point being, I just don't think you're shooting distances are going to be much more the 150m.
Just my opine - others will have different ones too.