As an Electrical Engineer, I see no high level of skill required (as far as the wiring), you would be working with an existing schematic, so it would really only be a paint by number level of skill needed. Maintain the color legend for all wiring and make sure you keep it neat (I can see this turning into a hopeless rats nest of wiring if you let it get away from you.

The artwork (playfield) is an entirely different kettle of fish. You will need a very accurate set of photos to be able to recreate the playfield layout (holes and correct placement of components).

Finding and refitting mechanical components will also not be easy (unless someone with a Gemini is willing to provide a LOT of details regarding the mechanical guts and possible donor sources)