No X codes, To early. Check for the single 3/8 fuel line, 7000rpm tach, 507 and 508 frame mounts, speedometer cable should come from the trans tunnell area at like an angle toward the passenger side. (Muncie) Does it have the original radiator? Should have a 3 core with the passenger side tanks having the C B code on them. Manual steering pitman arm should say 3953227 for the fast ratio steering. If the power disc brakes are original the booster should say 9024 on the little flag tag and the master cylinder should say 309. My car is 11D. #547891 so we are REAL close. Buy Jerry MacNeishs book. A lot of good info. Sam
Just a couple of notes. A tach is not a good indicator for a Z, as early builds did not require the installation of a tach.
On the radiator issue, the CB will at least indicate a small block radiator, so look to see if has the UH radiator tag. http://www.camaros.org/coolingsystems.shtml
Pull the back seat and look for the yellow partial X code on the passenger rear seat bulkhead. This and the other items should give you a much better idea on what you have.
Good luck on your findings!