Barb, John Houston (or Huston as he preferred it) Marley was my grandfather. I think he was Archibald's son.
It seems somewhat less likely that he would have called himself Marley if his real name was Cunningham or Houston. I think one possibility is that Sarah, Archibald's wife, was not really 60 years old. Sometimes census takers actually put down the same age for a husband and wife regardless of their real ages. Also, the ages of John and Franklin in 1850 do not seem to agree with later censuses very well.
It's possible that John was named Huston after Sarah's (his mother's) maiden name.
The story in my family (my mother was my source) was that four Marley brothers, who were originally from England, came north from Tennessee at the time of the Civil War. From records it looks to me as if Archibald Marley and his sons William, James, John H. and Franklin went to Clay, Missouri 1850-60. John Huston went to Mills County, Iowa in the 1870s.
My father (his son) wrote in some notes that he thought the spelling was Huston or Huseton, with a question mark. John used Huston as his first name when in his 70s (1910 census).