Okay, I actually submitted the rule proposal that was voted on and accepted for Classic legality.
Here's what it says: The model must have been designed, built, or flown before midnight December 31, 1969. That means if the model was designed just prior to midnight on December 31, 1969 it is still legal.
Now the rest of the story: My proposal actually read: Designed, built, and flown prior to midnight on December 31, 1969. When it was sent out for a vote, someone had mis-typed it to read Designed, built, or flown prior to midnight December 31, 1969. That was the wording that was voted on and passed. Because of that a design need not have ever flown to be considered legal. That proposal also stated that that cutoff date was a permanent one for Classic.
If you designed and flew that ship at the 1964 Nats in Senior (Which was won, by the way, by Barry Simmons of New Jersey...) then it is Classic legal. You do not need to prove it any further. Your word is plenty good enough.
Bob Hunt