Through the forum I jumped to the Italian Replica Car Club site and found this interesting info:
"Please look at the
www.dft.gov.uk/dvla/vehicles.aspx (CHANGED TO
https://www.gov.uk/vehicle-registration) website in section Motoring/ Registering a rebuilt vehicle, kit car and kit conversion - section kit conversions.
This has changed to include body kit conversions, and affects all body kit conversions finished or future builds, on unaltered chassis or monocoque bodyshells, if the general appearance of the vehicle has changed. For example F355,F40,F360,F430,Dino on Toyota MR2 or Ford Cougar - 250 GTO on Porsche or Datson - 308,F40,Testarossa on Pontiac Fiero - Dino, 250LM on VW Beetle
I have a received a reply to a number of questions I asked the DVLA in an email, which I can forward it to anyone who requests it. In short it says:
1. If the body kit fitted alters the general appearance, and the monocoque bodyshell or chassis has not been cut into, then the V5 should be sent to the DVLA with a covering letter detailing the changes , pictures of the finished car, and of the build if you have built it , and copies of any receipts you have. They will then amend the V5 under model to reflect the altered appearance, but not the Manufacturer.
2. If the monocoque bodyshell or chassis has been cut then it will have to have an IVA to register the vehicle.
3. All local DVLA offices are closing in the near future and I am informed that any inspections of vehicles to determine if IVA is required , will be done at a MOT testing staion.
The DVLA has not indicated what the price for this might be."