I wouldn't give up on it just yet. The harness should be fine, distributor should be fine too once it dries completely.
I would buy 2 oil changes and same for trans. Change engine and trans oil, do a tune up with fresh plugs, shift through gears let it run for a couple minutes then change engine and trans again. Don't forget about the rear end also, prolly just one change needed for it tho. Maybe leave the plugs out and use a shop vac to try and suck moisture from the cylinders.
A good wash with a hose and/or some time with a shopvac will do alot. There's not too many crevices you can't get to. Rocker panel, and torque boxes are the only spots that come to mind that you can't easily get to within minutes.
I know its alot to take in on top of everything else you're dealing with but I would def not give up on your fastback.
Hell, I have a 302 distributor sitting around I can send you man if you want it. Think I even have the pertronics stuff for it. Yours if you want it.