Looking for family info of OLE S. LEE

Hello. I don't have much info but perhaps someone can help. David A. Lee, my husband, in Rhode Island, is son of: Kenneth John Lee, (Minnesota) son of: Harry Orvel Lee, & Selina (Running) (Minnesota/Wisconsin) is son of: Ole Syvertsen Lee, & Ingeborg Helene "Belle" (Thoen) (Baldwin, Wisconsin). We know Ole was born September 1850 in Norway. We have surmized that he came to USA in 1869. He and "Belle" married on October 08, 1874 or 1876 in Wisconsin. He was a blacksmith. They had 5 (?) children. What we don't know is what his last name was originally. My husband was told, approx 20 yrs ago, that the last name was originally something like "Lieftren" (sounded like that, no idea what the spelling is). Apparently, Ole shortened it to Lie (Lee sound) but later changed it to Lee to avoid the mispronunciations he was encountering. A suggestion of "Liestrand" was offered, but we have No Clue!! Does anyone have any other suggestions on how/where to research this?? We do not know where in Norway he was from. Thanks for any ideas you may have.... sha.