Check in Classic American magazine, as they have a directory which might have contact details for a club - On sale in WH Smiths,its a club called the Pre 49's you need to look for. The club link isnt working at the moment
They have a massive library of old books and a wealth of info with many old cars over here.
I used to deal with them about 7+ years ago but dont have contacts any longer.
Go to this show at Knebworth on Sat/Sun this weekend, info as 'Rally of the Giants on this link.:
http://www.knebworthhouse.com/events/events.html Sorry cant help more but I worked with the yank models from 60's, but know these guys could help.