I know this isn't what you asked for but it might be useful to you in the future if you don't have it already.
Tarbolton churchyard has only one noted McWhinnie in the MI book:-
Er to mem of John Oliver d 7 Jun 1866 aged 71; also Helenora Hamilton McWhinnie his wife d 11 Mar 1865 aged 71
According to the IGI, James McWhinnie son of James Mc W & Agnes Downie was born in Ayr in 1761
I have Downies & McWhinnies in my family although I haven't researched the names much but they were mining families and I have Annie Downie (h James Pearson, my gt gt g/parents) b Stair in 1802. I also have a James Pearson married to Janet McWhinnie (parents Jas McW & Agnes McCrone) in New Cumnock. My family were in New Cumnock, Dalmellington, Stair, St Quivox etc - all mining villages but I know the Pearsons were thought to have come from the north of England.