Good morning Mike,  I saw your listing on the MMD and just might just
have the part you are looking for. I converted my Stroud Metrostyle
Themodist piano in to a full Duo-Art a many years back and I think
I simply boxed the extra and odd and old parts.  (If you choose, you
can see an image of my piano on my web site; it is a full orchestrion
now that plays many styles of rolls.)

My piano started life as an upright and was built in 1923.  We would
have to make better contact to make sure it would work as I don't quite
understand your listed drawing.  It might make better sense if I had
the part setting in front of me.

If you don't get a good response from others, email me back and I will
start my search.

Gary Stevenson
South St. Louis, MO