Looking for information re my GG Grandfather William Spencer (1816-1868)

My GGGF, William Spencer, was married to Bridget Meara (or O'Meara) on 02/18/1844 in Cournaganeen (Bourney) in Tipperary County.   William and Bridget had several children, including my GGF William (b1847 d1897), Theresa, Mary, Patrick and Henry (Harry).  William died in 1868 in Roscrea.  

It is known that, after my GGGF's death, the family (except perhaps Henry) immigrated to the United States on the "City of London" out of Liverpool, arriving in New York City on October 15, 1872, eventually settling in St. Louis, Missouri.  

While I am certain that my GGGF William was born in Ireland, I have not been able to locate any information re his parents, or other direct relatives, earlier than his 1816 birth date.   Any assistance in this area would be most appreciated. 

William appeared to own/rent land in Coolroe and to also have been a steward for D H Vaughan of Goldengrove.  Any detailed information confirming his connection to the Vaughan family or the properties he helped manage would also be welcomed. 

Thanks

John D. Spencer, St. Louis MO USA

jdspencerstl@att.net