Your ROI isn't going to be measurable. You're going to get in it, and never want to sell it.
EFI conversion won't be that difficult, and they are extremely reliable. There have been lots of conversions, just do a search. You can go the cheap route if you already have a 302 block, and just swap out the parts. Or if you find an 87-93 Mustang that's been wrecked...swap the whole engine.
It'll cost you a little bit...no, quite a bit to get it reliable to the point of a DD (Daily Driver), but well worth it in my opinion. The Bronco has so much more class than a J**P, or any other 4x4 short of an H1.
...Even then, some will disagree with me, and say it IS the best.;D