In searching for my great great grandfather, P.J. Sheridan, I have come across a portrait that includes P.J. Gordon. it is entitled :
Portraits of the Fourteen Traversers in the State Prosecution of the Land League.
It is among the holdings of the National Library of Ireland. Here is the URL: http://catalogue.nli.ie/Record/vtls000153893
Also, if you google "the fourteen traversers in the state prosecution of the Land League" you will find that there is an upcoming auction at Whyte's in Dublin on April 21, 2012, and it appears that they are auctioning this portrait, but I cannot find it in their catalogue. You will also find other references to this portrait as well as digital images, albeit very small.
I have a bar poster that has Parnell and a circle of associates that has PJ Sheridan but alas, PJ Gordon is not on it.
Hope this helps!