While this may not be enough proof that this is "your" John, it should help with the family.
"History and Topography of Dauphin, Cumberland, Franklin, Bedford, Adams and Perry County" by I. Daniel Rupp, 1846. From Chapter 33, p 483 entitled "History of Franklin County" 'Upton, a post village in Montgomery Township...about 2 miles from here, in Peters Township, reside the Mr. McCulloughs whose ancestors had been abducted by the Indians.'
From "Franklin County Will Abstracts, 1784-1826"
Will Book A, p 66-7. Will of James McCullough, Peters Township, Cumberland County, w/w 2 May 1778, w/p 15 Mar 1786. Wife Martha. Sons John and Hance the plantation I now live on. Daughters Jean McClellan and Mary Forster. Brother Archibald McCullough. Grandson James McClellan. Jannet Harren and Rachel Harren each to have a young heifer. James Holliday. Exec: Sons John and Hance and my trusty friend John McClellan. Wit: J. Maxwell, John Hunter, and John McClellan.
Will Book C, pp630-1. Will of John McCulloh, Senior, w/w 4 Sep 1822, codicil dated 3 Jan 1823, w/p 13 Feb 1823. Son John McCulloh. Wife Elizabeth. Daughter Susan Parkhill. Land in Indiana County, PA. Sons Joseph and James. Exec: Son John and son in law John Parkhill. Wit: Christian Cougher, Jacob Hess, William McClellan.
Records of the Upper West Conococheague Presbyterian Church, Mercersburg.
31 Oct 1773- Martha, daughter of John McClelland
5 Nov 1775 - Rhoda, daughter of John McClelland
18 Aug 1776 - James, son of John McClelland
__ Feb 1780- Hance, son of Janet McClelland
13 Oct 1782- Nancy, daughter of James Parkhill
13 Feb 1783 - John, son of John McCullough
19 Feb 1789 - Susanna, daugher of John McCullough
__ Jan 1802 - child of Joseph McCullough
28 Mar 1807 - child of Josiah McCullough
4 Oct 1809 - John, son of Joseph McCullough
12 May 1810 - Alexander White, son of James McCullough
__ Oct 1811- David Fullerton, son of Josiah McCullough
4 Jul 1812 - Eliza Cunningham, daughter of John Parkhill
__ Sep 1812 - Mary McKinney, daughter of James McCullough
8 Nov 1774 - John McCullough and Mary McKinney
4 Mar 1788 - John McCullough and Eliza Cunningham
1 Jan 1801 - Joseph McCullough and Margaret McFadden
25 Apr 1810 - John Parkhill and Susanna McCullough
John McCullough, Ruling Elder for 24 years died 4 Jan 1823