Hi
Death records are held at the Masters Office in the relevant Department of Justice in the area.
Here are the contact details for the Masters Office in Cape Town
WARNO STEENKAMP WSteenkamp" at "justice.gov.za ASSISTANT MASTER
You can try to email him quote the estate number and name, according to the Estates List he did leave a will so there should be some useful information on it.
If you don't get any help direct from the Masters Office (they are very busy) you can try through
www.eggsa.org, they offer a service whereby they can get copies of files for a very reasonable fee.
I would also guess that by now the file has been transferred to the archives, as his estate seems to have been settled, but has not been captured onto the online database yet.
Good luck