You might peruse the thread below. Perhaps there is some info you might glean:
Any castings name & letters/ numbers on brake plate? I think is a Triumph and they come with 3 different types of cable pull. Nothing on either the plate, or the shoes. I PM'd the OP of the mystery plate. He was last seen on this Forum in 2016. Not much hope he can be found. At this point...
www.accessnorton.com
For my brake plate, the conclusion is the shoes are no longer available.
Slick