Insurance for a 99 2.7RS Evocation?

[madcaplaughs]

Does anyone know the best (or indeed any!) insurance company that will cover me for my new prospective purchase? The car is registered as a 1985 3.2 Carrera Coupe but has been backdated to look like a 1973 911 RS. The engine, gearbox, exhaust, suspension are all standard for a 3.2 Carrera. The bonnet, boot(?), wheels, lights, are all period 1973 RS and the interior is stripped and identical to RS.

All online quotation systems kick it out as uninsurable and of course have no contact details so you can talk to anyone. I have tried Peart who won't insure it unless I never use it for business purposes and restrict my mileage. I won't use it as a daily car but I might want to use it for the occasional business trip.

Any help would be appreciated.