Willis Kirk b.1774 in Virginia: Does anyone have actual paperwork that references his father?

Question

I've seen about five versions of the Willis Kirk lineage on various user-generated sources; some have been debunked, and no one seems to have anything DEFINITIVE linking Willis Kirk to his birth-parents.  There has to be some sort of hereditary deed or other paperwork floating out there in digital form.

The Willis Kirk I'm referring to is the patriarch of the Pennington Gap, VA Kirks.  Haven't gotten anywhere with census records.  His father may be a John Kirk or a Thomas Kirk, however, like I said, there's quite a few conflicting sources.

Answer 1

This says that the progenitor of the Kirks who were in the New River Valley and later Lee County, Virginia was one John Kirk, b. 1754 in Fauquier County, who married an Elizabeth O'Brien and died sometime after 1832 when he applied for a pension for his Revolutionary service.

Comments

It's certainly possible that Willis comes from John and Elizabeth. 

The main issue that makes it questionable is Willis' birth year - if it's indeed 1774 - falls about a decade behind the marriage.  Like I said, it doesn't make it impossible, BUT, if true, suggests a lot of different alternate scenarios: 1) That Willis was born from a previous union, 2) That he was, indeed, born to Elizabeth, but was something of a very complicated situation, 3) That his birth date falls a decade or so after the date listed at the Kirk burying-place (his grave marker is reported to be illegible), or finally, 4) That Willis is the offspring of another Kirk family.  There were multiple John Kirks in the general region, and I can see how it might be easy for folks to get them mixed up over time.

There have been reports from users - which I can't verify - that Willis is not listed in John and Elizabeth's family bible.  I really wish I could find a photocopy of this document, but no one has ever been willing to offer it up as proof.