Playing devil's advocate here, but I can't see anything in particular about Margaret (Hutchen) Looney's will which shows her to be the wife of this particular John Looney, rather than another John Looney? (William Looneys had sons John, and John s/o Robert Looney/Jane Kneen bapt 23 Jun 1750.)
Was there a deed (marriage contract) or anything else which identifies her as being married to the John who was the son of John/Margt Kelvie?
Sue