'85 GLS wiring and fuel question

We bought the RX7 last year at a charity auction. They claimed it wouldn't start as the engine was froze up. Well, we got it home, replaced the battery and fuel filter and it fired right up! Anyway, it still has lots of things that need attention; first the wiring has been torn out and haphazardly put back in so the gas gauge doesn't work; and the second is when trying to fill the tank, it constantly backs up and shuts off the pump so we're only able to get a couple gallons of fuel in at any one time.

Is there a good place to find out how to rewire the dash and any clues to what's going on with the gas tank? Thanks