Just bought a used Scott 2016 and nothing has changed; the listings are still as murky as ever for South Africa.
Below is a bad scan of Scott 66:

Note that the top projection/rhino horn is gone from the "A"s in "AFRICA", the bottom of the "U" is rounded off.
So yours is 64a or 65a (English inscription singles). Don't necessarily go by the colors, since these come in shades like all the other issues. Gibbons Commonwealth lumps both of these together, actually, and the general South Africa catalog is no better.
I'm guessing the difference follows what the other later shilling values look like. That is, the shading lines around the borders and in the vignette are distinct square dots in what Scott calls the 1954 printing:

The original 1949 printing has horizontal shading lines that are slightly broken into square dots:

Need more magnification, but I hope you can get the idea.
So yours is a 64a by what I can tell by the scan. Value is like 25c for a single, $15-20 for a horizontal pair, less for a vertical pair. So don't break up pairs to fit in an album.