Offferdahl/Offerdal, Ole Ivarsen

Good Day, I'm new to this site and not adept with it. Also I do not understand Norwegian, and I have difficulty reading script, even in English. I am the great grandson of Ole Ivarson, the son of Ivar Olsen Offerdal and Berthe Kerstine Anfindsdatter, born 11 Feb 1841, in Laerdal. He was the oldest of a large number of children, and I believe the first to leave for the United States. When, from where, how and to where I would like to find out. Ole's first appearance in the US is in the 1870 federal census listed as Ole Everson. He is living in Perth Amboy, New Jersey, which is a port town, not far from New York. He worked in a Fire Brick Yard. He has a wife named Catherine who was born in New York, about 1838, and whose parents came from Newfoundland, Canada. We think they were english. In subsequent state and federal census he is listed Ole I Offerdahn, Ole E Offerdahl, etc. His wife Catherine is listed as Kate or Cath. In all these documents he is employed as a Dock Laborer. He never seems to have left Perth Amboy. He died 4 Jun 1894. The family legend is that it was from a fall at the docks. His widow was listed in the 1900 census as Catherine Everson. Their three children used the surname Everson. He apparently kept in touch with his family, since his descendants stayed in touch with his brother Ivar Olsen Offerdal. Ivar settled in Norman county, Minnesota, USA. He became Edward Ivar Offerdahl and raised a family of 7 girls and two boys. Some inquiries about Ole have already been made, through a cousin of a cousin, with no results. He apparently does not appear in the 1865 Norwegian census, & no records go his emigration have been found. I have not found anything here in the immigration records. I would appreciate any help.