Hey, I try to help and I RARELY get angry, but gosh - half the Swedes in the county are named Petersen, and the other half Larsen. It is a state law that Swedes name at least one son Hans, and the next one Peter. My great grandfather was born in 1837. My neighbor's was born in 1904. (Their family tends to get pregnant in high school.)
ANY kind of date would help. Saying he was your GGF's nephew narrows it down to 110 years. Modesto was founded in 1888. You are asking people to find a needle in a haystack.
If he was a state congressman, write to Sacramento for records. You might get an official biography.