http://www.rootsweb.ancestry.com/~momiller/
And this is the site for Miller County Historical Society.
http://www.millercountymuseum.org/
Of course the other impediment to finding his grave may be Lake Ozark which now covers a good chunk of Miller County. As I understand it an effort was made to relocate any cemeteries the lake would cover and that may actually help us as pretty detailed records were kept of relocated remains.
John R.