Definitely check in at mustangii.net, the Facebook group is now growing inactive since the site forums are back up & running. Very helpful people, many of them obsessed with the II. My 78's wiring was also a complete mess, but I was able to straighten it out in a couple of days. Mostly you'll find grounds out of order (especially in bulb sockets), and potentially a deteriorated instrument panel housing. You'll probably find it isn't as bad as it seems (unless it's all rat-chewed and water-logged), since the wiring is so simple on those old cars compared to modern multi-computer monsters.
Which engine do you have? My v6 spare engine was also seized but primarily from a little surface rust, and a broken plastic cam gear. A day of soaking in wd-40 in the plug holes, a new steel cam gear, and a few turns of the breaker bar and I was in-business. Of course yours could be worse (even a cash-for-clunkers car purposely destroyed) but if it's a v6 it may be worth a try.
I restored mine (an amateur resto, interior & exterior) and it pretty much needed absolutely everything mechanical (engine, transmission, exhaust, starter, alternator, power steering hoses, brake booster / master / lines / hoses / calipers / cylinders, gas tank, fuel pump, carb, shocks, battery box, minor rust repair, differential rebuild... and pretty much everything cosmetic (the interior was pieced together from several old cars, my first headliner install, carpet, vinyl dye by the bucket, dash pad, new racing seats, seat belts, gauges, heater core, A/C hoses, radiator). In retrospect the $400 I paid for it wasn't much of a bargain, but it only took about a year for it to be in really good shape, and gets lots of compliments wherever it goes. The next year I custom fabricated a turbo setup for the v6 so now it's pretty fast too.
So fire away if you have any questions, as LILCBRA mentions, it's only a few of us, but we've been through the paces.