I remember reading that article. Obviously the "third black man" is Dre with Eminem. However, if all of those people are on ONE painting, then it wasn't a Pac poster since Eminem didn't blow up until 1999; rather, it was a painting that Riskie did for Death Row in years after Pac's death. However, if they are separate paintings, then yes, it's possible that the Biggie and Puffy ones were "Pac posters."
I remember reading in an older issue of VIBE where Spice-1 says he saw what was to be cover art for the Hit 'Em Up single, where Biggie's head was on a pig and Puffy's head was on a snake... I wonder if Riskie was responsible for that as well.
However, I acknowledge Riskie's talent as an artist, but after the Makaveli album cover poster was sold originally for $70.99 then significantly dropped to a much better price without the signature, I feel inclined to keep my money from now on.