Be sure to disconnect battery and what not before you begin on the wire repairs. If possible, I'd just cut out the chewed up wires and solder (w/heat shrink) in new wires in place, and then tuck them into a nice wire loom or some such.
I recently picked up an 84 El Camino SS which had sat for a few years and the mice/squirrels/whatever went to down on the hoses and wiring so I know your pain!! lol :-/
