Don't know if Hudiburg Chevy kept their records from 1969, but they are still in business. Midwest City is just outside OKC. In fact, if I am not mistaken, Steve Hudiburg is heavy into muscle cars and has a restoration / sales business in Edmond, OK, another suburb of OKC. Look here:
http://www.worldwidemusclecar.com/INDEX.HTML
Not promising anything, but if you can get ahold of Steve, perhaps he could let you know if they have records from 1969. Worth a try if you are serious about this car.
Hope this helps someone.