Fellow CAF member, Thomas Ward, did the legwork on tracking down the likely origin of this unpublished piece. Here's the write up from his facebook page(slightly edited and used with his permission):
"A Tale of Two Covers -
One of the last series that Dan Smith did for King Features was a series called “Love Through the Ages” which began on March 5, 1933 and ended on April 16, 1933. I acquired the large artwork and written in pencil on the top of the page is “KFS Front Page # 1 – Love Through the Ages Release March 5” also on top in red pencil is “Release March 5, 1933.” I never could find the image in the online newspaper archives until I started researching other pieces from that series and found that the printed March 5, 1933 cover has a different image. So, I concluded this had been a prototype and was ultimately rejected."
The published verison for March 5, 1933 is elsewhere on the CAF. It's a beauty and much more appropriate beginning point for the series. I can see why King Features ultimately went with it instead.