I have done my due diligence for the checklist for this set, but I have unfortunately came up short.  Anybody who can fill in the holes would be greatly appreciated.  Thanks in advance.

Are these those photos players sign for autograph appearances? If they're photo paper and not card stock and aren't graded by PSA/etc., they can't be included here.

They are not made for autograph appearances.   They were released as a set of four large cards in a plastic sheet container.  They are made from card stock materials and not photo paper.  See the link for a photo of how they look for distribution.

https://www.ebay.com/itm/1990-Tv-Sports-Mailbag-San-Francisco-Giants-Will-Clark-Mitchell-Reuschel-Butler-/173775112297

Shane, the fact that the packaging calls them "Glossy Pictures" doesn't help your case.  You probably want to point out that, for 1990 anyway, the backs are printed and they were a numbered series, as can be seen in this auction:

https://www.ebay.com/itm/154594858404

These appear to meet the criteria set forth in the FAQ:

Frequently Asked Questions

Photographs are defined as a collectible that measures longer than 5 inches on the shortest side and longer than 7 inches on the longest side.

To be included, there are two criteria that photographs must meet. Note that both criteria must be met in order for the photograph to qualify for listing:

• Is it ok to add entries for photographs?
  1. The photographs must be printed on cardstock, not photo paper.
  2. The photographs must be printed as a consecutive set (sharing design elements from one photograph to the next). It should not be just one stand-alone photograph.

Thanks for the clarification and approval and glad to hear I wasn't wrong since I normally am.  

Now that we got that out of the way, can I get some help please. Thanks in advance.

Seems like something DaClyde might have some info on 

Tim Peichel from Super Collector Catalog was kind enough to give me his research information on file. 
A fellow member told me #97 was Bo Jackson.

I found Greg Maddox and Barry Larkin on eBay for sale but unfortunately the back of each card wasn't readily available to see and the seller would not disclose the information to me so I can't get the card number for either player.

Ah, indeed Tim was the guy I was thinking of! 

I guess I get an A+ for my due diligence since I got no other contributions from any other members.  Add them to the checklist if you later come across a player that needs to be added. 

Who's "Greg Maddox"?