I am the great granddaughter of Henry Przybyszewski, who is the son of Walter, who is the son of Thomas. I believe Walter's brother Joseph is your direct ancestor?
Walter and Joseph's parents names, Thomas and Katherine, came from Walter's MN death certificate. There was no maiden name for Katherine though. Do you have Joseph's death certificate- maybe that has more information on it.
On Walter's son Henry's MN birth certificate, it lists parents birthplace and Walter's said Kuznia, Wiekopolskie, Poland. This is pretty much all I know about pre-Minnesota Przybyszewski's but I'm starting to look at DNA lines too.