Trying to find Johannes Thorsen

My husband's great grandfather we believe was Johannes Thorsen in Norway. We have his birthdate as slightly different than the one we find in Olen, Hordaland, Norway. Ours is Dec. 1837, but a baptism record shows May 24, 1837. In the USA his last name was House, but some older relatives had told us he was John Thorsen House. We are wondering about records related to his immigration to the USA. In the censuses here he said he arrived in 1864 or 1865. We believe he would have come with his wife Julia Valborg Rasmusdr. We cannot find him in the 1870 census in the USA, but can in 1880. Any help with when he arrived and with whom would be helpful. Thanks so much for your wonderful help, Cheryl House