HK Porter Locomotive Research Begins
This is an excellent page listing a number of other websites that have info on the HK Porter Locomotive Works of Pittsburgh, Pa where the locomotive that is in Rivefront Park in Sewickley was built. This is the beginning of my research into the local Porter locomotive. Nothing here strikes me as the same exact model as the Riverfront Loco, but a few are close.
Here are a couple of other good link on Porters:
RR Extra Porter Page