I think you are right about the MPU, looks like an early System 11 (nothing) Board. I read this from Pinwiki:
“System 11 (nothing) MPU
This picture shows the early System 11 MPU. There is a later revision available which has an additional jumper W16 located between the 7 segment diagnostic display and the relay. The pictured early PCB has a trace routing error to the sound ribbon cable connector. If you use it with a later system 11A sound card you will get no sound because the sound card doesn't get reset properly. If you wonder why your High Speed doesn't beep when turning it on this one is also the culprit.”
Can anyone confirm what version MPU this is?
CD8A0F86-B3C3-4C10-A7E7-5EDAD88A75B4 (resized).jpeg