Every bit of data is of importance, even when it doesn't match up with what one already has, Robert.
Alas, I don't believe that the Robert and Ellen I found on the 1880 Tioga County, PA (USA) census was the same as your gr-grand uncle and his wife. The couple I found had 6 sons and 2 daughters, all born in the US between 1855 and 1880.
Would you be interested in contributing to our on-going DNA project? We'd love to be able to add your data to the site, and there are excellent DNA testing labs in the UK.