The manual steering wheel was a larger OD to relieve the strain in turning the wheel for the weaker sex (whom ever they may be). As to body parts I can not advise as I work in generalities as opposed to specifics for this kind of think.
To my knowledge (like I say I no body man) from the rag joint up the steering columns are the same (interchange number 1229). From rag joints down Chevy made two different Saginaw PS boxes (605 small gear used on Camaro and Nova and the 800 large gear used on full size and light trucks) all of which are interchangeable in terms of bolting to the frame. However from a numbers matching restoration I couldn't advise. I would suspect any '65 to '74 L-6 PS GM box (interchange number 707) and '68-'69 Nova pitman arm (they are different also) would be a cheap source of parts. The PS pump and brackets are specific to the car in groups by years SBC before '69 used the short water pump which required different brackets and pulleys than after '68. Any non-metric pump (no O-rings on the hose) made after '68 should bolt up to your 605 PS gear box.
The brackets for 69-72 P/S on small block cars are pretty much the same on Camaro, Chevelle and Nova models. The pump itself is the same, but the cans are where the difference is (b/c of how the return line gets routed.
The P/S rag joint is the same on 65-76 models, and is still available from GM and reproduction houses.
Swap the box, the rag joint and pitman arm and you're set. Columns and steering wheels are the same.