I've got the same question about how picked your compressor as Spencer, I don't mind using junk yard parts so much as I've got an older, dirtier truck but I need to know what I'm lookin for before I go buyin a bunch till I find one that fits.. Obviously.
Thanks to this thread, I started (barely) this project. I've done about all I can before I pull the trigger on the compressor, but I did a ton of research on exactly which compressor will work and hopefully give you the least amount of trouble.
take a look at my thread for the homework side, and use this thread for the actual fabrication side. once life calms down for me, Ill tackle this project and maybe make a sticky- worthy writeup.