Dave from The Topps Archive Blog. Good blog check it out. It is by far the most interesting.
For some reason there is a hoard of the '62 printing plates and I believe it extends past the baseball and football issues. There are a lot of proofs from this year as well available in the marketplace. I suspect they were found at the plant of the original printer's, possibly Zabel Brothers in Philly. The plates are not in the Guernsey's auction catalog so that is an incorrect bit of detail in the listing. I believe they entered the hobby en masse about 1991 and seem to recall one dealer selling huge lots of them in SCD at the time. A nice companion piece but there's a lot out there on these so would not overpay.