The name Kufel with one f is Polish, and two f's is some times the english version.
I have found out from Carrie Taylor that our joint Kuffel roots are from one Paul and Elisabeth Kuffel of Wisconsin per 1870 census highland township, Iowa County. The Kuffel family is from Lubiewo and Gross Byslaw, Westprussia, Prussia which is not too far from Bydgoczyc. You are right that it is now a part of Poland.
I am looking for two items, one of which is how they got
into the country ie which boat, the other is related
family of Paul's children and Paul's parents.