I bought a complete operating system last summer for $800 that included the box & pitman arm, pump, cooler, pulleys, brackets, lines & steering shaft with bearings. They are all off of a 73 EB.
So, first off, if you do a PS conversion, your best bet is to get every thing from the same vehicle. Idealy you would like to get it from a 73-75 Bronco. This is a direct bolt in as far as the box goes. It is also hangs down the same length that your stock manual box does. Don't get a system from a 76 or 77 because the steering linkage is different. Those years they used an inverted Y steering system and 66-75 was a T system so it will go in flawlessly. As for doing an F-150, Toyota, Scout, etc. or any other system, there will be fabrication with all of them. The question is how good are you and do you think your skills are up to doing them. Now personal opinion, experience and preference tells me that the 73-75 Bronco is the easiest, user friendly and least time consuming swap than any of them. I did it to mine last year and absolutely love it. I helped a guy about 3 months ago put the Toyota system in his and it was billed to be "the easiest on the market" conversion. Well if that was easy, then my 5 month old son could do the PS swap that I did on mine, just put it that way.
So with that, here is a quick walk through to do the Bronco PS swap.
The parts you need are the box, pump, pulleys, lines, brackets and steering shaft from a 73-75 Bronco. The steering shaft has a rag joint that will give you problems unless you modify the front inner fender to accomodate it. You will have to cut out a portion of it to get the rag joint to clear the wheel well. The other thing you will have to do is cut a portion of the inner grill where the front of the box will hit it. The PS box is about an 1-2" longer than the manual and also a little wider. So you will also have to modify your radiator a small bit with a finess touch of a ball pene hammer... or have a radiator shop do it. So with those only set back said, here is how easy it is:
1) Remove steering shaft & old manual box. Pull fan & pulley off. (this would be a good time to also replace the old 4 blade fan with a higer efficiency 5 or 7 blade fan)
2) Install new box (this will bolt directly into the original bolt holes for the manual box).
3) Install new pully and fan.
3) Install new steering shaft & shaft bearings.
4) Install pump & lines.
5) Fill pump & start engine to fill box. Top off pump.
6) Enjoy your new PS.
This took me a little less than 3 hours from start to finish. It will take you longer because you have an older EB than mine. I have a late model 72 that has the wheel well, inner grill & radiator set up for the ps that was introduced in 73. So that was a blessing for me. If I were to make a guess, I would say that with cutting and other minor modifications, you are looking at a weekend if you are unfamiliar with these types of mods. Otherwise you could really do it in a day. The 'Yota swap that I helped with took us a complete weekend and isn't half as clean as an installation that mine is. Personally, I would not be happy with the way it is if it were mine (Sorry to you guys who have done the Toyota conversion) but thats me.
If you want a complete walk through just PM me and I will write something up for you.