69 Cuda - Entire Electrical

Rebuilding 69 Cuda from the ground up and looking for electrical advise. Here is the dash and components along with the electrical wires, back view...This is all the electrical I have. Do I need an entirely new harness or just additional wires to attach to what I have? Any recommendations at all (what I need and where to buy) would be appreciated. Also, should I buy new gauges or should I attempt to work with the original? I'm lost and just don't know where to start or what I should and shouldn't do...Haha. Thanks.

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