Steve, while waiting, I have actually found some information.
I would refer WAGS members to Vol.1-2 of the Newsletter (Casting Call) .pdfs. where this pan has been featured. In 2004, it was debated whether Griswold or not. This style lettering is considered large Serif style raised letters and numbers.
What I do not know, is whether there is more clear information or consensus in the intervening 10 years.
You may want to re-measure the pan at the widest, and longest spots to affirm your initial measurements.
PS Wags Members... I am finally doing a lot of Reading of all the back issues of the Casting Call, in hopes of providing a mini-index, so to speak! :)