Ok, that helped. I cut my cable and mirrored the pins now OMS 2.3.1 can see my MT-32pi and I can play a mid in Musicshop.
So how can I get Hoyle Classic to use this? It says it needs Midi Manager and the extension is enabled, I just don't know how to configure it. The game starts then says Could not find Midi Clients or Ports.
Thanks!