OK, now that we have you scared, but with an open mind
time for specifics!
First you need to look at the title and compare them to the VINS (yes, pural).
Read this page:
http://www.camaros.org/numbers.shtml (CRG is a wonderful resource!) take pictures of dash VIN and cowl VIN. If car is apart, you might even be able to see the firewall VIN. Plant letter and last 6 digits have to match. It is common for 1st gens to have rust in the dash area and the sheet metal replace, so you have to inspect the dash vin tag area and see how it is attached. Take pics of the front and back as much as you can and post for review. We do it all the time in
http://www.camaros.net/forums/15-tag-team/
Next, Metal! So if the car has finished paint or primer, take a Rockauto refrig magnet and check: around rear wheels, lower corners of door opening and door, lower front and rear of fenders and rockers. Basically anywhere you cannot see the backside of a panel.
If the shell has had panel replacement, you need to check fit and finish. Is it on straight? gaps look proper? Look behind panel and where is was welded on. Correct welding is to drill holes, weld on primer, the plug fill the holes with MIG, then grind smooth. If, you see sloppy weld work, it will be an indication of other poor work done on car.
Lots of good examples of weld work here:
http://www.camaros.net/forums/133-build-projects/
Don't despair too much if you see sloppy work, most can be fixed, but you don't want to pay extra for sub standard work!
Additional info on body issues:
http://www.camaros.net/forums/12-body-shop/
You will see people take on rusty projects, with just the rust is holding it together, After they take it apart, just a few good panels are left. Then using a body jig (sold separately!), the start with the floor and build a brand new Camaro from the floors up. Brave souls!
Lots of other forums to browse!
http://www.camaros.net/forums/