I suspect you're having problems finding names on the census because you're putting in too much information.I have learned that if nothing comes up with the spelling as we know it, try different spellings or leave the first name off entirely.Some of the enumerators seemed to use "creative" spelling, as they heard it pronounced, or they used only initials.I went back and checked today and the 1870 census for Enterprise twp is still not working.
If John H McGhee was born in Aug, 1858, it would appear that his father John was living at least to Nov or Dec 1857. In 1850 it shows John with property which Elizabeth has in 1860.You might be able to find land records.Does Linn County have a genealogical/historical society?You might see if they could help you.
I don't think these folks are related to "my" line, or if they are it is back a few generations. There are several Magee/McGee/McGhee lines that were in Virginia & Kentucky. Your "Northern MO" caught my eye, as my line were in Harrison & Gentry Counties (just north-west of Linn) and the Rev. David Magee/McGee line was in Macon County (just east of Linn).Both of these lines are from the Madison Co KY Ralph Magee line, which goes back to Ralph Magee in Surry/Sussex Co VA.