Looking for Burial Place of James O'Neill and his wife Mary O'Kane

I will be making a brief visit to County Tyrone in September with the hope of finding the burial site of my great-great grandparents, James and Mary O'Neill who lived in the subtownland of Derryhoogah in Garvaghullion.  I know from the Canadian marriage record of one of their daughters, that James was deceased before 1863.  I do not know when Mary died.  They had the following childen:

Edward born 1813 - went to seminary in the US and was a priest in New York where he died in 1862

Hugh born abt 1815 - remained in Ireland; married Jane McKee abt 1837; death unknown

Rose born abt 1818 - immigrated to Chicago, Illinois - never married, died in 1868

James born abt 1820 - married Sarah McKenna abt 1841 in Tyrone; immigrated to the US; death unknown

John born 1822 - immigrated to Chicago where he married Ann McGillen (Co Fermanagh); died in 1887

Margaret born 1825 - married Thomas Mullin; immigrated to Montreal, Canada

Henry born abt 1826 - remained in Ireland; married Mary Jane O'Kane (3rd cousin) in May 1875; died Dec 1875

Bridget born 1834 - immigrated to Montreal, Canada where she married Thomas McKenna; died 1910

Alice born 1836 - immigrated to Montreal, Canada where she married Patrick Mullin in 1863; died in 1903

I would be grateful for any advise or local knowledge.

Joan Bentley Curtin