Since no one else will give you turbo info, I will. I've ran imports for years and though I've only turbo'd 1 car, I've been up on my F/I game for awhile.
First you do not want twin turbo. Nobody should even run twin turbo unless it's a track car. They are made to make boost down low and up top, the first smaller turbo spools fast, but can only hit a certain amount of CFM (we'll say 350 [air unit] CFM) the bigger turbo now spools ungodly slow (it probably peaks @ 4-4300rpms) but the CFM of air is upwards of we'll say 600. They are really for people who need instant power, and then need big power on straight/long wide open throttle runs. The big turbo eats a lot of fuel and air, and is pointless for a bronco. It'll probably blow the motor before you make any high power...
Also, you will have to figure out a way, and which side you will be running your turbo on. An inline 6 is the best bet for a turbo motor (6 cylinders worth of exhaust compared to 4 on one side of a V8), but you can have custom manifolds fabbed up (which will be some big $$$) to mount a turbo and piping. The issue would most likely be though, is that your will have to remove your A/C in order to fit it. I would try to stick with a "Log" style exhaust manifold. No crazy piping, it's a simple basic design that takes up about as much space as a regular exhaust manifold.
Turbo size, and inlet/exhaust are very important. You will need to research these #'s. I am not going to break it down for you, it will take me forever going back and forth with you and questions. I would start with sites for evo's, sti's, turbo DSM (eclipses, talons, etc etc) they have a lot of turbo information. You are going to want something that is small & spools fast. Something between a .48 & .60 trim.
T3/T4 and T3/To4 hybrid turbo's are very popular because they can spool quick and run good boost #'s. I'd take a look into those before anything else. The #'s after the T usually represent size. T3 turbo's are pretty tiny, you can run those too.
Please though, take the time to research there is a lot that goes into turbo'ing anything. Even if it was a lawn mower. You are much better off with a S/C like others said, the turbo you won't have instant power. S/C's go by RPM, there is no spool. When your RPM's go up, your boost goes up. With turbo's it takes time for the exhaust gasses to spin the turbo, but there is no parasitic draw as you so put it.
Also, both of them will be downing your MPG's, and most likely will max out your fuel injector cycle. Also you will need a higher CFM fuel pump for either. More air = you need more fuel. Otherwise you run lean and hot, and won't make the power.
I would go research till your fuggin fingers fall off. Just google turbo 351's or turbo ford 400m's (same block, same set up) you're bound to find something...