John Hanson Ike

John Hanson my great great Grandfather was born near Oslo Norway in 1856. The 1880 Census says he Arrived to the US in 1868. His mother died shortly thereafter and he was moved to another home; he then took on Ike for his last name, (from the First name of the man of the house). They lived near Osceola, Iowa. I have tried many ways to find him, census, ship, immigration, records etc, but don't seem to hit on the right one. In fact I have a hard time finding a John Hanson living with an Isaac (long for Ike?) at any time. I found John H Ike in 1880- living with another family as a laborer, and then I found he was married in 1880 to Carolina Anderson (Norway) and living in Dakota Territory through a state census. With the ship records, I don't find a family with John as a 11-12 yr old boy in 1868. I would like to find someone who might have some knowledge of him., or tips on how I might track him down. Thank you. sincerely, dp