I've already made some suggestions, you might try them first.I suggested you post a query asking for help on the 1880 census, and in checking your message history you haven't done that, yet.
What was your source for the full birth date of George?There is no Shannon county in TX.There is a town named Shannon in present day Clay Co, TX.But, Clay county was formed in 1857, so if George was born in the town of Shannon, TX, in 1856, he was born in Cooke Co, TX.
Do you know when and where George died?
I would find an 1860 census index for TX, Turpin probably isn't all that common, and look up all Trupin families, especially in that area of TX.Find one that has a son George about 4 years old.
I didn't have an area in MO, so I did it for the whole state of MO in 1860 for every Burnett family, and it is probably more common then Turpin.Yes, I did find the right family.We just have to hang in there and keep trying. (^_^)