SA octane rating is 93 or 95, this is the RON rating, RON stands for something like Research Octane Number and is used in most parts of the World. However if you compare this to the USA specifications you need to look at the Anti Knocking Index (or something along those lines), to convert the two you need to work of a base. I have found that a ratio of SA 95RON fuel = USA 91 fuel is most used.
Regarding race fuel, you can get some shell, but you need contacts and I also heard there is one BP dealer who is selling 98RON fuel. But you would need to do the research there.