I'd investigate the William and Sarah Glasgow listed in the Clay County 1880 census. They are living two households from Nancy and Sarah Langley. I suspect the Langleys and perhaps those Glasgows are related to Rachel and Robert McAbee based on family oral history. In fact, I also suspect the Lells, a few household back may also be related.
William and Sarah Glasgow might be the parents of your William Thurston Glasco/Glasgow. The timing seems about right if he was born in 1884, and the names fit.