Does any know whats involved in retro fitting air con to a Sapph cos?

I'm restoring it nut by nut anyway and its being stripped back to a shell for paint so this would be a good time to do it.

Any help would be appreciated.

 

bulkhead is different ,but you could get most of the bits off either a 2000e sierra or a 2.0dohc 4x4 sierra