Bob, if you're looking for historical Firebirds, the first two 1967 Firebirds would be a must for this display. They aren't restored correctly, but they are still significant to the story of the 1967 Firebird.
Another significant 1967 Bird is the one in the Daytona museum, repeatedly claimed to be the first Firebird built (I've never seen the VIN) and it paced a few races at Daytona. I'm not sure you could finagle them to haul it to Rosemont IL for the show though, but it might be worth a try. Honestly, this car would get more exposure in 2 days in Rosemont than it gets at the Daytona museum in a year.
The first Fitchbirds were evaluated by Pontiac as a potential "special" Firebird (the car that would eventually become the 1969 Trans Am). Pontiac rejected the Fitchbird, and it slipped into oblivion. Fitch sold a few conversion cars to recoup his tooling costs. I'm not sure if that qualifies as a part of Pontiac history, but it's a possibility.
There are a couple excellent examples of finely restored 1967 Firebird convertibles in Tyrol Blue, and this would make an awesome display if you could find someone could create a life sized cardboard cutout of DeLorean to prop up next to the car. [img]<<GRAEMLIN_URL>>/smile.gif[/img]