I am not an expert on this but did a little research, some say this swap requires quite a bit of changing starting with a new rag joint, I see others talk of pitman arms and complete steering linkage for correct geometry, I don't know how much of their claims are correct. This is one conversation I found and I'll post the link below --
Alright, here's my experience and I'll go into as much detail as possible unlike most of the other people online who leave out a lot that they assume is common knowledge...
First of all, manual and power boxes have different size output shafts and require different pitman arms. If you already have a ps box, they say your original pitman arm will switch right over.
Any box up to a '92 will bolt directly in place of a 1st gen box... only difference between the years is the hose fittings which changed over certain years from male to female, AN to O-ring, and SAE to Metric. (I don't know all the specific years since I only have experience with one)
You will need a new rag joint GM#7826542 (I used a DORMAN 31011... same thing).
As I was going from manual to power and couldn't use my old pitman arm anyway, I bought the MOOG K6582 that everyone reccomends. Some others are available for different lengths I'm sure, but this one is closest to stock at only like 1/2" off... (you cannot use the stock one from (at least a 82-92 anyway) because the connection at the drag link is different... idk about other years.
My details: I used a simple 3.25 turn box from a 90 Firebird that I picked up for 25 bucks shipped to my door... a little work, some wax and grease remover, and a can of paint and it looks like new. The total steering geometry is what figures your ratio, not just the box. There are long and short pitman arms, and also steering arms. My original manual box was a 6.5 turn (i'm sure to ease the work of no power assist by having a low gear) and long steering arms to help speed the ratio back up at the tires gave me a 4.5 turn at the steering wheel. Since I used an almost stock length MOOG pitman arm, that didn't change much, but the extra 1/2" did help a little (longer arm makes for faster steering since the end travels a farther distance for the same amount of turning radius). Overall product with the replacement 3.25 box, stock length arm, and my stock long steering arms, made for a hair over 2.5 turns lock to lock at the steering wheel... which is what everyone reccomends. They say any quicker and the steering becomes twitchy and hard to control. If I had gone with the "quick ratio" box, then my car would be [censored] near undrivable. So make sure you match your box to your other parts... quicker number isn't always better.
As far as hoses go, since my 90 box uses the O-ring style connectors (and i'm installing an 01 LS1 motor with the factory pump still attached) I was even able to use my stock hoses that come from the factory 2001 rack and pinion setup... the sizes are the same (all metric -box and pump). The return line was simple, it fit right in and just trim to length and reattach to the resevoir with the original hose clamp in place of the line that went to the ps cooler in the factory 01 setup. Pressure line is a bit trickier since the length and bend of the tubing needs to be modified to reach the port on the box. There may be other years of hoses actually designed to reach to a box instead of down to a rack, and may still be the correct metric thread (maybe from a 90s car). I've read that for boxes like mine anyway, the two fittings are just an 18mm x1.5 and 16mm x1.5 metric O-ring connectors if you want to make your own or have custom lines made. The other guys that need to make the SAE conversion, or the AN to O-ring, can do like everyone says and call Lee Mfg. (I've also read of adapters picked up from Advance Auto and such that do the same thing if you want to search for the posts in other forums).
