(1)where can I get a fairly detailed drawing of the power steering set up on my 75. (2) any suggestions/warning on changing the distributor....keeping it stock I think mine is bad.car runs rough. When I took cap off inside was rusted and damp.

Besides the GM Service manual for your year I get a lot of information like that from my Paragon parts catalog.  They have lots of great drawings.  Some others also have good drawings but if I do not find what I want in my GM manual I pull out my Paragon catalog.

Just curious, was it damp as in water/moisture or oil or? The only rusty distribs. I've ever seen were units pulled out of engines at the wreckers. Even my 70 year old dead flathead distribs. are not rusty. 
Dave

What specifically are you looking for for the power steering? Are you adding PS, and need bracket/pump info, or something else? I can get you diagrams of all of the system components this evening.
As far as the distributor, a little rust isn't cause for alarm, nor is a small amount of condensation inside the cap. Up in your area, moisture can get in there. It can cause misfiring, tho, until it dries out.
If you have some major rust forming on the metal parts of the dist, then it might be time to either rebuild, or replace the distributor. Rust, or rusty looking deposits on the inside of the dist cap, comes from rust slinging off of the advance weights, under the rotor. HEI systems will do this. Again, if the rust accumulation is major, you might want to replace....but if it's minor, a little clean-up, and lubrication will prolly suffice.
If swapping the dist, first mark the location of the rotor tip. You need to line it up with something on the engine, or point it directly forward, or directly rearward, toward the firewall. Do not mark it on the distributor itself, since you are changing that. I usually point them straight forward, toward the carb. When you pull the dist up/out, the rotor will turn slightly. Take note of that, as you will want to line the new rotor up in the same spot when installing, and it will twist back to what was the original location...theoretically. One of the problems involved with this theory is that the oil pump shaft will also spin a little when removing the dist, and getting the new dist to line back up to that can be aggravating, but most of the time, it all lines up just right, and the dist will slide right back in, and the rotor will be pointing to the same place the old one was.
Good luck!

here is the steering components 

Tanx Bob!! 

I'm replacing the pump,cylinder and hoses just want to make sure everything go back where it's supposed . No it's not oily may be original distributior.