Assuming either signature is real, I would say he more than likely had it signed pretty recently, since the car has been restored in the not do distant past. Assuming this is the same car. I would find it hard to beleive that a car that did not sell on Ebay for 35K would all of a sudden be advertised at 175K 3 months later.
Don't know what happened to the last link but here it is again:
Camaros.net Discussion
And heres the last Ebay auction for the car with the signatures unfortunately the pictures are gone:
Ebay Auction
Assuming the partial Body number in the ad is correct (12467 NOR 2985??) that car isn't even a Festival car as it's probably a late March car.