No, I don't believe they do still exist. They would have been updated yearly until '70, which was the end of the line for the Coronet kits.
Yes, they were release announcements but they were apparently either testing the waters or based on mis-labled moulds, depending who you talked to.
And, as others have said, obviously if they were out there they would have been reissued already. No one would have left an sure money maker like that in storage.