need written or pictorial proof of vehicle being driven by frank
sinatra or used in promoting his tour.

I think you'll find it was a De Tomaso Deauville. There was an article
in the Australian's weekend magazine on the 9/10 August, and it
mentions an italian sports car that was actually meant to be a 'decoy'
vehicle that Sinatra climbed into by mistake. I recall seeing some
black-and-white footage from the time and was a foor-door vehicle.