Sorry, Rootsweb reformatted this message into one long string that I cannot edit.
Welcome to "Irish" genealogy!
I have given you some links below that may help you. What I have found is that there were no Larkins or Callaghans in Boston in 1851 (the year of Griffith's Valuation), so they must have moved there sometime later. The following links may tell you where they came from. See if any names look familiar to you. Irish repeated names in families.
Here is a link that will give you more information about the location of Boston in Kildare: http://www.seanruad.com/cgi-bin/iresrch
Griffith's Valuation lists 18 Larkins (leaseholders) in Kildare in 1851 (this should lead to relations of your 2x great grandfather):http://www.askaboutireland.ie/griffith-valuation/index.xml?a...
The two names in the above that are not Larkin indicate that they leased from someone named Larkin. Look at the details for more information.
The following link will give you all of the names of leaseholders in the civil parish of Oughterard, including Boston. This may lead to more family connections.http://www.failteromhat.com/griffiths/kildare/oughterard.htm
The following link will show the inhabitants of Boston in 1851: http://www.askaboutireland.ie/griffith-valuation/index.xml?a...
You can check the 1901 census at: http://www.census.nationalarchives.ie/search/
This may tell you any family members who stayed in Ireland.
Griffith's Valuation is the only census substitute for the 1800s. There are fragments that exist, but none for Kildare that I know about. Other places you may check are:
Irish Family History Foundation (pay per view)http://www.rootsireland.ie/
Marge in Southern California