Ian - I think Mark and I have the later edition Motorcraft point plate (and mine is actually an electronic Duraspark II version). The replacement vacuum control parts we are referencing are made by a company named "STANDARD MOTOR PRODUCTS" - and the one I've got on the T-bird is a "VC-223". The operating linkage extending into the distributor is a formed flat - not a wire rod.
Have you come across a replacement that looks like this? It can be disassembled and re-shimmed.
Steve Metzger Tucson, Arizona