This pennant was indeed made by Advertising Flag Co. of Chicago, IL, a.k.a., ADFLAG. Additionally, it was made ca. 1960, as this maker also made a 1960-dated "WORLD CHAMPIONS" variant featuring this same artwork. Toward the middle and end of the 1960s, they made other Packers pennants; including some referencing their Super Bowl wins.
Here's a link to my post on ADFLAG if you crave more info on them:
https://pennantfever.weebly.com/blog...tising-flag-co
There's a pennant library at the back end of this post that features a dozen or so NFL and AFL pennants by ADFLAG made during the 1950s and 60s, including the above described pennant.
It's a cool pennant, nice pick-up!