Roger,
I have no idea when it went to the USA, what was it’s registration number there ? It was originally registered 479 BTR a Southampton series issued from May until June of 1962 which would tie in being sold by Wadhams Ltd. and being a May delivered ‘B’ spec. (no wire wheels) . It was held back for a couple of months for rectification work, what that was I have no idea.
If you have any early owner’s names I will search what records I hold.
Laurence