Parents of Mary Agnes Power

I am looking for any information on the parents and siblings of Mary Agnes Power, born about 1854 (her US death certificate in 1934 lists her age as 80) in or around Moneygall.  Her father's name was David Power and her mother's name was Mary (surname unknown).  The family story is that, as teenagers, Mary and her sister (possibly named Florence) witnessed an assassination.  Their Catholic priest helped spirit them out of Ireland to save them from being killed because they had seen the murderers.  They immigrated to New York City in 1872.  Mary became an indentured servant to pay off her passage.  I have no further information on her sister. 

Mary was married in Brooklyn, New York in about 1876, to an Irish immigrant named James Joseph Hoolehan (I know nothing of James Hoolehan's origin except that he was born in Ireland about 1840).  They had five children:  Michael Joseph, Mary Agnes, James Francis, Richard, and William David.  Mary and James and their children moved to Florida in about 1883.  James died in about 1889 and Mary died in 1934.

I have found on RootsIreland, a birth for a Mary Power in 1851 in Toom, Toomevara, Tipperary.  Her father was David Power and mother was Mary Britt.  Sponsors were:  Lant Meagher and Mrs. Kilmartin.

I'm not sure this is my Mary Power because of the date. 

I also found a death certificate for David Power, age 69.  He was married.  He died in Moneygall on 20 February 1892.  He was a shoemaker by trade.  Witness to his death was his son, David Power.  The death was registered in the District of Shinrone, in the Union of Roscrea, in the County of Kings.  The age and place fits, but I don't know if this is my Mary Power's father.

Any help that will help me break through this brick wall will be greatly appreciated. 

Charlene