I don´t know if this helps you, but I have here in Finland a 7ECA (s/n 1198-77) with Hooker five-point harness. It is installed in September 1998 using STC SA312CH (Hooker Custom Harness). The list of approved airplanes includes also 7KCAB.
If I had understood right, you can use my plane as a reference for authorities in your country, because this installation is approved by one european CAA before EASA. So this installation is now legal in all EASA-countries.
Please, send me your e-mail adress if you will have more information. Mine is: mikko.jaakkola(at)pp4.inet.fi.
-mikko jaakkola-