If you really want to sell if, I'd bite the bullet and fork over the dough to get the engine fixed/replaced, unless you can do it yourself, of course. A solid, reliable, running Bronco will open up your potential buyer market tremendously.
It's hard to give any kind of price estimate from just the few pics you posted and the short description. My Bronco, for instance, looks like a $20K truck in pictures, but she's a 20 footer that I paid $7K for! LOL How is the paint on your ride? Interior? I do know that having a 4 speed manual makes it pretty rare, at least in my neck of the woods (Alabama), but buyers around here want that V8, so it's kind of a trade off. It really just depends on your local market and how many are available and at what price.