This 1979 baseball mockup, courtesy of the aforementioned savedfrommyspokes, is clearly close to a final design for the 1979 set. I quite like it:
1979 has always been my favorite design from the "blah" era (1976-80) and that design is even better than the issued one IMO.
Hall of Famer Glenn Hall. "Mr. Goalie" adorns this particular Topps creation, courtesy of Mr. O, as is the final creation below as well:
What's not clear is what this design was being developed for. Looking at his St. Louis Blues years (1967-68 to 1970-71) and the Topps and O-Pee-Chee cards from that time frame, he was a bit grayer the last two years, so I am thinking this shot is from his first or second season in St. Loo. A quick check of the away unis during that time shows he is possibly is wearing a hybrid but I think it's actually a playoff uni from that year. The number on the sleeves for the Blues white tunics was a 1967-68 feature only but the fat blue stripe being sandwiched by thin gold on the sleeve may be from their playoff run that year as a much simpler design was replaced for the postseason.
If that's not a design mockup for any of the sets issued by Topps or O-Pee-Chee during 1968-70 (which were very blah compared to the above design) then it may have been for an insert or "special" card. The 1968 O-Pee-Chee set had a second series that Topps did not and within it were some specials. Here is Hall's; I love how his first name is misspelled:
Another possibility is the Push Out insert from the same year, only issued with O-Pee-Chee cards:
Or it could be for something else entirely. I have to say the action shot on the mockup is much more appealing that the dour, five-o'clock-shadow tinged portraits on the above two cards.
We have another very nice looking mockup, or maybe even prototype with the next subject, Francis Asbury Tarkenton:
No clue what that mockup is supposed to represent, maybe a special set for a third party given the prominent NFL logo. All I can say is that is one nice looking card and the border looks like it almost could have been designed with some type of sparkle in mind. Not sure of the year as their uniforms were pretty similar for the years (1968-71) Fran scrambled for Big Blue.