BYU Studies (Vol 36, Issue 4, Article 7, 1996) published a wonderful article about the publication of the first portrait of Oliver Cowdery titled “James H. Hart’s Contribution to Our Knowledge of Oliver Cowdery and David Whitmer,” by Edward L. Hart.
It is available online here: http://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=3157&context=byusq
I highly recommend the article for anyone who wants to know more about this fascinating story.
Here’s the first LDS publication of the portrait. It appeared in the October 1883 Contributor.
You can see a copy online here.
One detail to note is the upper right corner, which portrays the angel showing the plates to the Three Witnesses. Of course, this is how the witnesses originally described the event. Much later, David Whitmer said there was a table with artifacts on it, etc. I suggest a reason why in my book, Whatever Happened to the Golden Plates?
Here is how the portraits appeared in the Contributor, which you can find at this link:
Source: Letter VII