Thanks Jeff, you're always helpful.
This is not directly Mustang related, so I understand if you don't add further to this.
The said distributor had an Australian application and was used on 351C 4V engines imported from the USA that were installed in local high performance Falcons. It is referred to as a Motorcraft distributor in the attached snippet from a '75 Australian Parts Catalogue. From July '73 a locally manufactured Motorcraft/Bosch distributor became standard (refer photo).
I was attempting to identify the American application to assist with locating one.