Although I don't think any domesticated dog would be able to survive the Serengeti, if I had to put together a dog by crossing breeds, one thing for sure I would consider is size. Meaning 24 to 26 inches at shoulder, 55lbs to 75lbs is what I would go for.

Here are the breeds I'd put together:

1. Catahoula (hunting abilities/nose)
2. Black Mouth Cur (hunting abilities/nose)
3. Spanish Alano (hunting abilities/jaw/toughness)
4. Wolfhound (hunting abilities/coat/strong/lean)
5. Ridgeback (hunting abilities/speed/lean/heat tolerence)
6. Saluki (hunting abilities/speed/lean/heat tolerence)