Looking for information about great grandfather

Please help me find family information about my greatgrandfather. His American name is Severt Johnson He was born in Norway on 12/12/1853 and immigrated sometime between 1853 and 1887. My grandmother told me his name was changed from a Norwegian name which could have been one of the following: Blexrud, Blixrud, Blekstad, or something similiar with Norwegian letters, or y's or j's It is possible he had a brother named Hans Johansen Blekstad who immigrated here in 1860 and was born in 1842. Hans may have married Joren Aslaksdtr who was born in 1840. It is possible that the name Johansen was associated with them and that they came from a place called Eidsvold, Norway Severt had 8 children who all were born in Houston County Minnesota. His wife's name was Minne Can anyone help me find any links to these things? Thankyou much JLR