Can anyone offer help with Pervangher ancestor?

From Glynnis Anderson-Smith, United States

My great great grandfather was Nazaro Pervangher, born 1840 (+/- 1) in Airolo. Somehow he made it to Vicksburg, Mississippi between his birth (1840) and 1860. I found him on a census in 1870 with someone named Antonio but cannot find the relation or any other information on him. They married sometime in 1860 – 1870 and he died in 1890’s. I can find nothing on his immigration/passage into America. Can anyone help?