Why Chevy would think it necessary to do that escapes me. For every car they made there was a final unit. I do not believe any of those [many thousands] received a tag proclaiming it to be the last. In my 36 years in the hobby I know of no GM car so designated. At the time the car in question was built Norwood was still producing '69s and the '70 tooling problems were known.
The last '69 convert in our db, a much later build than this one, is over 6,000 units from the end of production. I will bet there was/is even a later one.
It is puffery, a BS story intended to hype the car.