Source, aged 77 at death in 1879.

SS: Finally found John's obit Coleraine Chronicle Saturday 2/22/1879
Feb. 15,1879 Finlay at his residence Long Commons Coleraine John (late of Ballystrone, Dunboe) farmer, aged 77.
Enjoyed our day in Coleraine. I left my Finlay stone in your car. Please save until next I return.
Will be in touch soon.
Sue

Name    JOHN FINLAY
Year of Death    1879
Group Registration ID    6942083
SR District/Reg Area    Coleraine
Deceased Age at Death    77
Image
John Finlay died 18/02/1879, age 77, Commoms, Coleraine, married, farmer, bronchitis 1 month, uncertified, no medical attendant, Elizabeth Finlay, Commons, present at death signed x mark

Could this be her death on the Pilot site:
Name: Mary Ann Finlay
Registration district: Coleraine
Record type: DEATHS
Registration date - quarter and year: Jan - Mar 1886
Estimated birth year: 1801
Age: 85
Mother's surnames:
Film number: 101593
Volume: 1
Page: 397
Digital GS number: 4200675
Image number: 00302
Collection: Ireland, Civil Registration Indexes 1845-1958

From SS:
Mary Anne Finlay died 1/3/1886, Rosemary Street, Coleraine, age 85, widowed, farmer's wife, old age and debility, uncertified, no medical attendant, Jane Finlay, Ballystrone, Macosquin, daughter, present at death signed x mark  
(I am confused by the death cert of Mary Anne Finlay in 1886.  We had her as the wife of John of Ballystrone.  And yet a Jane Finlay, daughter, was PAD - but we know that her daughter, Jane Finlay, my great great grandmother, was married to Samuel Clements.  SS replied: Mary Ann's death cert confused me also. I found her death notice in the Coleraine Chronicle but lost it on the plane home. It's the same date as the cert and puts her John of Ballystrone. I'll find it again, along with some others I lost, when in Coleraine. I've had other certs that used the maiden name of the woman rather than the married name.)  

doB from age 70 at death in 1897.

1897    McClements    Jane    70    1827    Coleraine    1;455 1Q    BG    ORDER THIS ONE - must be my GG GM, Jane Finlay    Derry FHC

Death Cert from Roscommon:
8th January 1897, Ballinteer; Jane McClements; Female; Married; 70 years; Wife of Labourer; Bronchitis, 2 weeks, no attendant; David McClements, his mark, son, Present at Death, Ballinteer.

No death notice found in Coleraine Chronicle for the three weeks after 8th January 1897.

Macosquin Presbyterian Church Baptismal Register has: Isabella Finlay, daughter of John and Mary Anne Finlay of Ballystrone, baptized 16/10/1829;  And yet she gave her age as 21 in her marriage certificate!!!!!

Source: SS
Isabella Finlay 10/16/1829-1866, age 36.

Also from the Pilot:
Name: Issabella Finley
Registration district: Coleraine
Record type: DEATHS
Registration date - quarter and year: 1866
Estimated birth year: 1830
Age: 36
Mother's surnames:
Film number: 101583
Volume: 1
Page: 393
Digital GS number: 4200215
Image number: 00088
Collection: Ireland, Civil Registration Indexes 1845-1958

Isabella Finlay died 2/24/1866 in Kiltinny, age 36, married, laborer's wife, pheumonia 8 days, certified, John Finlay, Ballystrone, present

Baptized 30/03/1832.

DoB from Susan Schiller.

Macosquin Presbyterian Church Baptismal Register has: Matthew, Eliza and John Finlay, children of John and Mary Anne Finlay of Ballystrone, baptized 22/12/1841.

DoD from SS using death certificate:
Death cert-died 7/18/1907, Gortcorbies, Drumachose, married 67 year old farmer, heart disease, daughter, Elizabeth, reported his death. 

DoB from SS.

Macosquin Presbyterian Church Baptismal Register has: Matthew, Eliza and John Finlay, children of John and Mary Anne Finlay of Ballystrone, baptized 22/12/1841.  So, if this lady IS a daughter of my John Finlay, she has to be either born later that the DoB SS has, or the Elizabeth baptised in December 1841 must have died.

DoD from SS, she died from pulmonary consumption (TB).

DoB from SS.

SS:  died 1907 in Gortycavan but no death in Civil Records.

1910 US Census East Front Street, East Hokendauquea
Robert Quigg, age 63 born c1847 Ireland, 2nd marriage, janitor public school
Eliza, wife, age 68 born c1842 Ireland, 1st marriage
John Finlay, nephew, born c1880 Ireland, single, laborer cement mill
Lived several houses from Thomas Finley and Annie Quigg Finley 

57 at death in 1906

SS: Mary Ann Quigg (date of birth can’t tell written on death cert) supposed age 57 years, Ireland-8/26/1906 Hokendauqua, Lehigh County, PA, married, daughter of John Finley and Mary Ann McDugal both born Ireland, Brights Disease, buried 8/29/1906 Fairview Cemetery, West Catasauqua, PA

Macosquin Presbyterian Church Baptismal Register has: Matthew, Eliza and John Finlay, children of John and Mary Anne Finlay of Ballystrone, baptized 22/12/1841.