[Dominik]

I learned now that it was CCX 3-3080, registered in South Africa in 1989, but with a VIN that was allocated by the local authorities. This cannot help you, sorry. The car apparently entered SA in 1987 but was only registered in 1989. This VIN was used in Germany in 2003.

I found an exerpt from an interview with Peter Bayer, then the owner of CCX (the full interview was here on CC):

"• Was the original mold pulled directly from or measured from CSX3045 – The original “Splash” mold was. (1978)

• What, if anything, was changed in the CCX body – Like the original CSX 427 cars, the Series 1 and 2 molds had a drooped right rear fender; this was corrected on the “Plug” used to create the series 3 molds in ’83."

This does not confirm the age of your car, but shows that CCX built them as early as 1978.
Early cars had the E-Type torsion bar front suspension, but it does not say if the change to the later body version (1983) came in at the same time as the suspension change. 3080 had torsion bar.

I believe you contacted the CCX "registrar" here on the forum? Maybe his findings can place your VIN to the required date.

The only proof you have, or should have, is the old registration with a year in it. Or an understanding traffic department officer who accepts your supporting documentation.