The SADF wouldn't be dumb enough to get involved in this. The weight of the fighting and the casualties would all come from the South Africans after the Congolese fell to pieces in the first couple of weeks and everyone knew it. Look at the Katanga conflicts during the seventies to see just how pathetic the Congolese military was. They ended up needing to call in Belgian and French forces to restore order... which should tell you all you need to know about their military capabilities.