Here is a somewhat recent thread on these stamps you may not have seen-- note that post 12 contains a panel like yours, although with different players. Perhaps that forum member has some ideas on preservation and value related to his experience.
https://www.net54baseball.com/showth...ighlight=OMAHA
Check out the thread from a few months back, as it contains a lot of useful information.
I have several panels and individual stamps. PSA would not grade my stamps from the Chicago American, picture attached. SGC did, picture attached.
PSA will grade stamps from the Sporting News and one other magazine (I forget which - Detroit I think), but not from other newspapers.
I didn't submit my panels, but I'm sure they wouldn't grade them - you could try.
Good luck.