Your going to have to dimple the frame to make room for the powersteering box off a later model truck. Do a search for "frame dimple" and you'll get some pictures showing what I'm talking about.
For example:
http://67-72chevytrucks.com/vboard/s...t=frame+dimple
You might also do a search for "quick ratio steering box" or something along those lines to find steering boxes that will bolt in and be less turns lock to lock than the 67-72 boxes, if you don't already have a box. I can't remember what year the truck was that I got mine out of (73-76 maybe) but if I recall correctly, you want to look for a box that is just over 3 turns lock-to-lock. Also watch for the flared fittings, not the o-ring fittings (unless you want to have custom hoses made. And I think I recall a issue with the rag joint that can easily be fixed also. I dimpled my frame and loosely bolted it up, but haven't tried installing a steering column yet or running the lines.
Look in the FAQ if you don't have your column for a cheaper alternative for a tilt column from some early chevy vans also, if you don't have a column. Man this board is great. Good luck!