I collect Brown stuff and saw that pin, but passed. It is definitely not authentic from the date listed. The photo used is from a 1964 team photo shoot. Here is a team issue from that shoot:
It has been widely reprinted and was also used to create a press release for the Pro Bowl that year.
So the pin is an anachronism in terms of advertised date.
Now, as to the design, the 3" safety pin format was not used during Brown's career.