I have an "Abarth" style instrument cluster on my "Abarth 695" replica, but with Smiths indtruments. I see from you pictures that you have a mechanical speedo, which does make things easier (my cluster came with an electronic speedo). My son helped me wire the cluster, and we realised that the Fiat multi-plugs on the back of the Fiat instrument cluster match modern multi-plugs. So he worked out (from the wiring diagram) what wire in the CAR side of the multi-plugs did what, and then we wired up the instrument cluster, with matching multiplugs, to match the factory wiring. I think that with the exception of one earth wire, the whole "Abarth" instrument cluster just plugs into the CAR multi-plugs. Doing it this way made (eventually!) for a much neater and easier to connect/disconnect wiring system.