Hi Val,
I have found two Galloways living in Co. Armagh in 1864 when Griffiths Valation of the county was taking place. Not much more information on them at the moment other than that they were the head of the household in each case.
William Galloway lived in the townland of Ballynery, in the parish of Martiaghs and George Galloway lived at Ballygasey in the Parish of Loughgall.
Best Wishes, Chris