I recently purchased all the various pieces to redo my 68s AC system. It can get expensive and it's very time consuming looking for the factory correct parts. There's some common things between the 67s and 69s birds, but a lot is specific to the first gen bird's. If you're open to a system that looks close, it may be easier to find a full Camaro system. I saw most of the parts from a 68 Camaro on ePay the other day for around $500.

The correct 68 bird, exhaust muffler, POA valve and a few other things are very tough find. I'd say to get everything you'll probably spend $2,000 or so, if you want correct. It took me almost a year to find what I needed.