I wonder if the one reproduced by Fireforce Ventures are accurate. The ribbing doesn't seem to be accurate, as it goes all the way from the top to the toes. Opinion? https://www.fireforceventures.com/South ... p_510.html
You are correct they are wrong. The SADF socks only ribbed at and rest is a tight weave, like hiking socks and a thicker weave on foot sole. The step out socks are fully ribbed but are only ankle high and a thin sock.
There was a set on BoB. Or you could try one of the local surplus shops. The problem in SA are the guys don't yet realise the need for full SADF kit collection.
However there is something interesting, as these socks look the same as the ones you showed, which seem then to be late 80's/90's.