Currently Doing the connecting Job
This is very funny as the pic you have is the same pic I saw in Craigs List here by LA. From that pic I bought my Police Trainer. Same cabinet and same console. Maximum Force Console and a Police Trainer main unit with a 33" monitor.
Since the Main unit (monitor/PCB) uses Molex for its I/O connectors, I went with Molex connectors ( your pic of the square connectors) I removed all the jamma connectors and wiring between the main and the console since there is far more wire in the Maximum Force console that needed by Police TRainer. All the molex connectors I used were from Radio Shack. The green guns (2) are just older Happs even tough they have 6 wires they wire down to 4 (+5(red), trigger(yellow), 2 grounds9black) and the optic out(violet) - green not used).
There's a 4 push button test board behind and to the left of the coin unit. police Trainer only has one line for "test" so only one switch needs wiring.
You may find the Happ recoil board installed to the left of the main PCb - mine has it although with a burned up #1 solenoid driver transistor - TIP-120 (Radio Shack carries it store-amazing). all repaired now. The green guns donot have the recoil capability. I've ordered the Red & Blue gun with recoil from a seller on Ebay. You can wire the green guns in to the recoil board just leave the 'Sol + -' disconnected and disconnect the 24vdc supply from ac mains.
I spent about 13 hours rewiring the console to main - not hard at all - just orderly cleanup.
Ask me stuff as you go through yours
Jack