On most of those cars in that era there was a lot of vacuum lines and those lines were controling emissions equipment. The dealer may still have the lables available because they are emissions related items. Go to your local dealer and ask the parts man. If that doesn't help, then call GM customer service and ask them. If you still don't have any luck you can go to one of the many Camaro shows I'm sure are around your neck of the woods and bring a camera. There is a guy (company) that specializes in decals and lables for classic cars. He may have something. I can't remember the name right now, maybe someone else will chime in that does remember. If not, do a search for classic car decals. If you don't get anyone else that has any ideas, I can give you the name when I get home and dig out the catalog.
With Chilton and Haines etc. manuals it can be hit or miss. But often they contain vacuum diagrams. You don't say where in Colorado you are, but in larger cities libraries often have an impressive collection of professional service manuals.
68 Coupe, 350 w/ Edelbrock Performer RPM heads, cam, intake, 700R4, Dave's small body HEI