Did you ever get any responses to your request? My research pretty much verifies what you have found so far. Mary was my Great Grand Mother, and John my Great Grand Father. I have tried to trace them back further, I have found Mary's parents (Daniel Hourigan and Mary Conic from Ireland and England respectively). Daniels parents were Daniel and Mary again, but I have absolutely no other information.
So if you have found anything I would like to hear. We are planning a trip to Ireland in the next year or two so would like to have some information so we can go look things up while we are there.