Hi pbspelly,
You may want to check with ebay seller thecatspajamas99 for a George Burke stamp of Billy Sullivan Jr.
Even though he currently does not have any Burke stamps for sale, I seem to remember him having a Sullivan Jr. for sale a while ago when I purchased my Zeke Bonura from him for my White Sox type set.
He does have a Burke photo of your grandfather (made from the original negative) for sale in his eBay store though...
http://www.ebay.com/itm/BILLY-SULLIV...item2eb807d048
Hope that this helps - and welcome to the forum!