You could try Silvia Vaccari at Campana e-mail
campana@campanacarrozzeria.it phone 059 828079 . They are in Modena they are happy to ship to UK, Silvia has good English. I got a box of parts when i was in their stock room last year on the centenary trip and they said they would be happy to supply direct to the UK. The correct all the reject chassis from the Maserati factory so are quite close with Maserati, but friendlier and a lot cheaper!!! I reckon the parts I bought there were all between 30 and 50% less than ES. might be worth a try!