Try to get in touch with Hammink Performance...
- Factory Five Racing Europe
They set in Netherlands, but are official dealers of FFR for whole Europe, and as far as I know, they are trying to get some kind of European Registration Certificate for FFR Cobras, that could allow any buyer of a kit to register their car legally in any EU country.
Probably it wouldn't work for you (as you bought a used car, and not a brand new kit by them), and I think their fight with public European Authorities isn't over by now, but maybe they could help in something...
Good luck...