I'd like to suggest Jim Feldman as a possible source of information about this car.
Jim is a very well known AC collector and restorer. He is a club member, but does not contribute to the Forum, prefering to communicate by mail and telephone. He has, or had (I believe) an example of EVERY automobile AC ever made. He really knows his stuff!
He lives in Portland, Oregon, about 50 miles from Salem where this car was located in the Ebay offering (above). Jim has 2 428's - Coupe and Convertible.
Jim used to advertise the ACOC in Hemmings Motor News, as the President of the American branch of the Club. It was through him that I learned of the existence of the ACOC.