Federal Loaded with Swift A frames, when using these you will not need solids, you are also good to go for any other plains game.
The other option seeing you are from Woodleigh country is to try and find Norma African PH ammo, loaded with 350 gr Woodies and throw a pack of FMJ solids in if you really have to.
I am not a fan of Woodleighs at higher velocities in real powerful cartridges such as the 500 Jeff, however the 350 gr bullets in 375 H&H work very well. They are also loaded to the ideal DG velocity of 2300 fps. The high sectional density increases momentum and penetration.
To be quite honest, you do not need solids for back-up shots on Cape Buffalo as a client with the excellent quality of modern expanding bullets.
Hydros and solids will put you at a disadvantage if used as the first bullet as you will be limiting your shot taking ability. If any buffalo are behind the one you target you will not be able to take the shot due to risk of wounding another due to over penetration. Same problem with the TSX. When they work they work well, however too many times they exit, sometimes the do not expand as designed and sometimes they loose petals.
You do not always have the "Perfect Shot" presentation and using the wrong bullets could cost you your dream buffalo or have you paying for a second unwanted one.
I would suggest the Federal loaded with 300 gr Swifts or the Norma African PH loaded with 350 gr Woodies.
Practice and make your first shot count that is all you need. If you accomplish that then no need to be concerned about a charge situation. If you cannot then don't take the shot.
Charges do not occur as often as we would like to imagine.
If the first shot does not kill the buffalo and follow up shots are needed, a client is better off using a premium soft point bullet. Again, over penetration is the main reason. Most buffalo are hunted either from bachelor groups or breeding herds and very rarely hunted as single animals. They 99% of the time run off after the first shot.
I always ask the question, if you as the client cannot place the first shot from an hopefully undisturbed buffalo into the vitals, where will you aim for your backup shot on a fast departing buffalo when using solids in order to stop the buffalo and not hit another in the process? For a client it is better to use expanding bullets and aim at something he can see, which in the case of a buffalo running away would be either of the hip joints or the spine just above the tail. Using a premium expanding bullet this will shatter either the hip joint or the spine, anchoring the buffalo and allowing for a finishing shot, without the risk of over penetration should the shot not go where intended. Both these targets are just under the skin so the greater penetration ability of a solid is not needed.
Even on a charging buffalo a client is better of with said premium grade expanding bullets. A buffalo will charge with his head up, nose pointed forward and will only at the last moment drop his head to engage with his horns. A now very nervous client who has not faced this before will find it very difficult to try and hit the brain if using solids as the head will be bobbing while the buffalo is advancing. Best shot for the client would be below the raised nose, in line with the neck(which dips quite low) and not lower than the two shoulder joints. Placed correctly this shot will pole axe the buff. Placed too low will still hit the centre of the heart slowing the buff and allowing for additional shot. Too high will still hit the neck vertebrae or brain. A premium expanding bullet will deliver more shock and shatter the bone/vertebrae more effectively than a solid.
Brain shot is only advised at the very last moment when the buffalo drops his head to engage you with his horns. Again a premium grade expanding bullet will easily reach the brain if the shot is correctly placed just below or between the bosses, depending on how close and how low the buff has dropped his head.
Stick with a premium grade expanding bullet and make your first shot count, that is all you will need.
Good luck on your hunt.