my cabs are very far away and I have no pics off hand. best I can really offer is that if he has a Midway JAMMA harness with all the correct plugs, and the Player 3/4 harnesses, those plug into the I-40 controller board (sits in the CP) and then I think all the stuff for the joystick connectors and the action buttons come off those.
the other harnesses for the N64 Memory Card reader and the coin door wiring will only depend on whether he has or plans to use the memory card reader and that he has the Midway coin door with the correct harness. and as such, if there's a Midway coin door, there's another harness that goes to the test switch panel for the volume up/down buttons.