Here is one option,
http://www.classicperform.com/power2.htm
http://www.classictrucks.com/tech/02...id_axle_chevy/
You can buy kits that have all the linkage and other parts you need.
http://www.dreamershotrods.com/power...yandgmcpu.aspx
This puts a power steering box on the outside of the frame.
Some of the guys have used the original steering column and cut it off just passed the firewall, pressed a bearing in the bottom of the tube to control the end of the shaft. From there you can buy ujoints and D-Stock or go with the U joints from a Chevy Atsro or GMC Safari van column and scrounge up what you need from a C10 to make up the rest of the shaft.
Research it here with the thread search tool. Several have layed it all out in good "How to" fasion.
I'm sure I left something out but others will chime in.