Its going to be easier to install an aftermarket kit than to hunt down the stock components. Costs depends on how much good used stuff you can track down. Buying new OE type parts is probably on par with the cost of an aftermarket system.
I went aftermarket for my non-AC truck, and I used
http://www.classicautoair.com/
They also sell new OE style stuff for restorations. The aftermarket system is decent. Not perfect by any means, but it works ok and cools well enough that I can drive my truck in the summer. 90+ degrees is somewhat rare here, we get a week or 3 of that most summers. High 80's is the norm.