John applied for a pension on Feb. 22, 1885 while living in Kansas. You could order his pension file from the National Archieves for a fee.

Regimental roster states he was a resident of Humboldt, Kansas when he enlisted.

According to 1880 US Census this is the only likely match.

John HELTON, age 39, born c.1841 in Mo. zinc smelter, parents born in Tenn.
Sarah HELTON Wife 40, born in Illinois, parents born in KY
Rosa W. HELTON, daughter, 12, born in Kansas
Charles HELTON, son, 7, born in Mo.
Emma WATERMAN, step-daughter, 15, born in Kansas, her father born in Tenn. and mother born in Ill.
Census Place: Baker, Crawford County, Kansas

And from a Civil war nut in Maine, thank you for tending the grave.