Looking for parish of ancestors who left in 1817-21

Hello, and greetings from Florida, 

I have been researching my family for about a year now, and have located the graves of James Parks b:1796 and Mary Ann Woods born a little later but I'm not sure when. The graves are in  in Pittsburgh, PA. They traveled to Pittsburgh separately and were wed in Allegeheny City (now part of Pittsburgh) in 1821. From that point forward I can connect the dots. However, I have no records of where in Co Tyrone he and/or she may have come from. There are quite a few Parks in the records I can find, and sorting out which one are my people from what I have availabe is a great challenge. 

Lucky for me, another distant relative found a reference to James Parks in a 100 years celebration book written about the history of Allegheny City in 1904. Here's what I know of James Parks life in Ireland. The good news is there are some specific and possibly unique details about his life in Ireland before coming to America. 

William Parks married Mary McGahey (weak evidence but all I have pre-James Parks) -> Son James Parks married Mary Ann Woods in 1821 in Pittsburgh. Mary Ann's father was Alexander Woods. I am not clear if Alexander or Mary Ann were born in Ireland or Scotland. 

I do believe the Parks came to Ireland as part of the Plantation event, but I have not evidence of that. They were Presbyterians in Pittsburgh. 

Two accounts are below, (but I wonder about the Derry reference): 

WILLIAM B. PARKS, a prosperous business man of Greensburg, was born September 13, 1838, in the vicinity of Courtney Station, Allegheny County, Pennsylvania, a son of James and Mary (Woods) Parks, James (father) was born in Tyrone, Ireland, where he was reared and educated, attending the common schools adjacent to his home. When twenty-five years of age he determined to seek a new home for himself amid new surroundings and accordingly emigrated to the United States, settling in Allegheny County, Pennsylvania, where he spent the remainder of his days. At the early age of fifteen years he married, and the death of his wife occurred nine months later. He married a second time, this wife dying one year later, survived by one child, and at the age of twenty-five years he married his third wife, whose maiden name was Mary Ann Woods, in Allegheny City, Pennsylvania, and they had eight children: Alexander, deceased; Martha, Nancy, Allice, deceased; Ann Jane, William B., mentioned hereafter; Thomas and James, deceased.

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Biographical and historical cyclopedia of Westmoreland county, Pennsylvania (1890)

Author: Gresham, John M. cn; Wiley, Samuel T. cn

Publisher: Philadelphia [Dunlap & Clarke]

Language: English

Call number: 31833022319484

Digitizing sponsor: Allen County Public Library Genealogy Center

Book contributor: Allen County Public Library Genealogy Center

Collection: allen_county; americana

Notes: This is a photocopied book. Photocopy lines and markings appear in the scanning. Print is light in book. There are multiple page numbering irregularities throughout the book. Page 513 is extremely discolored.

Pg 148 contains:

“THOMAS PARKS. Of the important business interests of Greensburg none are more Important than those of milling and brick manufacture, and a leading exponent of these lines of business is Thomas Parks, now resident of Greensburg. He was born just below Allegheny city, Allegheny county, Pa., February 19, 1841, and is a son of James and

Mary A. (Woods) Parks. James Parks was a native of county Derry, north of Ireland, came to the United States when a young man and followed farming and brick-making for a livelihood. He died in 1861 at the age of sixty-five years, he was a member of the Presbyterian church, a whig and later a republican in politics and married Mary A. Woods, by whom he had eight children. She was a daughter of Andrew Woods, who kept a public house in Ireland, and at fourteen years of age came over to this country with her brother.

Thomas Parks attended the public schools of Allegheny city for several years and then learned (he brick-making business. In 1867 he located in Greensburg, but in l873 removed to Paradise, where he now resides and operates a large brick-yard. He is a partner with his brother, W. B. Parks, in the flouring-mill business. They own and Operate the Greensburg Roller Mills. which is fitted up with the latest improved roller process and other modern milling machinery. The mill has a capacity of fifty barrels per day, does a large custom trade and supplies a wide section of surrounding country.

Thomas Parks was married April 21, 1864, to Annie E. Ash, who is a daughter of Jonathan Ash, of Donegal township. Of their marriage have been born ten children, of whom eight are living : William and Jonathan Winfield, who are assisting their father in the brick-making business; Mary A., Martha K., Lueian C, Samuel H., Keturah, and Charles M.