To make it safely driveable and reliable (enough), all it needed was a new master cylinder and brake booster, a carb rebuild (and fixing a buttload of vacuum leaks), an ignition refresh (plugs, wires, cap&rotor, and TFI module), a new fuel pump, and new rear tires. All "easy" items. But to make it usable and reliable, it ultimately took an engine rebuild, a fresh ECU (and a heated O2 upgrade), and a new catback too. Eventually it did need the brakes redone, some suspension work, and new front tires, but those were "after the purchase" issues. And then there's all the stereo/CB/interior/trailer work... and then the deer incident repairs... but that's a bit besides the point. I haven't done hard numbers but there's probably a good 5k-6k invested in it (includes purchase price, doesn't include consumables or registration)... not what it's worth, but not bad all things considered.
Is she perfect? No. But driveable? Yes. Daily Driveable? I'm doing it! (But only because I have my 1995 Ranger out of commission at the moment, not lining how much salt it's having to contend with
). Knock on wood, but I'd trust it to get me anywhere in the lower 48... which is what I strive for all my vehicles to be.
1984 F150: 300 L6, AOD, RWD. EEC IV / TFI, Feedback Carter YFA Carb. Stock everything but radio (for now).