Spalding Advisory Staff poster

[71buc]

I recently picked up this Spalding Advisory Staff Drysdale poster. It is 10.5" x 14.5" inches and appears to be an early 60s item. It is mounted to a 1/4" foam board. The front is covered with a thin sheet of plastic . The plastic covering extends about two inches all the way around the perimeter of the back of the poster. It is secured to the blank back with old masking tape. The poster beneath the plastic is in beautiful condition. However, the plastic covering it shows age, wear, and minor scuffing. I was considering removal of the plastic but I am concerned that I could be risking altering what is possibly an original cover to the item. I have seen the smaller advisory staff premiums this is obviously larger and more colorful. I think it may be a vintage sporting goods store display piece? Has anyone else seen this item or a similar one before? If so do you know if the plastic and foam backing is original to the item? Thanks in advance for the help