Not that it is any more likely to be correct than any other source, but my old copy of Krause (38th edition dated 2010) reads:
1960 - 1,024,000
1960 Prooflike - 70,000
1960 Proof -
Note VIP proof - 30-50 pieces
So that maybe where people are getting that figure. No figure against Proof suggests they have no data on that. They do not list Silver proof at all.