The crate motors are a good bet for your application. Thaey offer from mild to wild, depending on what you want to spend. They are set up for carberation, and come with a warranty from Ford. If you are building a 66 Bronco, you dont really want to mess with EFI - At least I wouldnt want to. It is a lot of extra money to spend to get that extra 1 or 2 mpg . It is true that all the EFI stuff was put on to decrease the emmissions, and to automatically fine tune the engine to the "nth" degree under different load conditions.

With a little practice, you can tune a carburated engine VERY well. My 66 Mustang Convertible starts, runs, and drives better that half of the new junk on the road, and its easy to work on.

Just some rambling thoughts....