Let's get back to the discussion at hand. I, too, was a pinball fanatic starting when I was a teenager. I then was lucky enough to get a job at a pinball arcade.
Part of my duties were to make minor repairs to the machines when they broke down, so I got the see the insides of many a machine. This was around 1980 to about '82, just before the electromechanicals gave way to computerized scoring, and the amount of interior wiring quickly became a lot less.
The majority of the wiring did deal with scoring. There were wires that had to run from every single possible scoring location, all leading to the scoreboard mechanism. There was also a rotating drum that kept track of special items such as when the chance for a free ball or "Special" lit up. It also helped keep track of mulitple points, like a 50, 500, 5000, etc., scoring target being hit.
Now as to machines and schematics, there was at least one oversize pinball machine commercially released called "Superman" (naturally). The ball wasn't a normal sized silver ball, but was a cue ball, and the flippers were very large -- almost like miniature baseball bats. If you can find a schematic or at least a picture of it, it might help with your plans.
BTW, the machine's size was about 3 to 4 times the size of the regular pinball machine.
