Brown(e) & McGuinness County Westmeath Ireland C1830

My great grand father was born about 1830. He named his parents as Thomas Browne & Catherine McGuinnes who lived & died in County Westmeath Ireland. . Nothing else is known of them or any possible siblings. I discovered on the "Valuation of Tenements" in the civil parish of Killua, a Thomas Browne and two blocks away a John McGuinness. The RC parish of Clonmellon is in the parish of Killua and so I wrote to the Parish priest twice, but recieved no reply. I then got a Westmeath researcher to do a search for me with the information known, but unfortunately he could find nothing. I have just discovered this website and am hoping that someone out there may have common ancestry with me. My great grandfather came to Australia about 1848 - 50, but I know nothing of any possible siblings. Maybe he had some that went to the USA or Canada?