Ashkenazi are usually found in Germany, Austria, eastwards to Russia.
Sephardic Jews came from Spain, Portugal, northern Africa.
I think circumcision was more common among non-Jewish communities in those days than it is now so there might not be any records held by a synagogue.
Has the Ashkenazi link been confirmed by DNA? Have you thought about trying to find a connection by using the results?
My DNA test showed 6% Ashkenazi, which confirms the connection to my gt.grandfather, but he changed his name and never married gt.grandma......still trying to find out just who he was!