Mary:
Welcome to Ireland Reaching Out!
Looks like the Kilmichael RC records on www.genealogy.ie start in 1821 but no baptismal record for Jeremiah is shown so either he was baptized in Kilmichael prior to 1821or he was baptized in a nearby parish. There are some Long records but not many where the father is Patrick or Denis. You mentioned a connection to another Long Family, was that thru DNA testing? If you have not had your DNA tested, you may want to go that direction. I would look at records in nearly RC parishes. You also may want to post Jeremiah’s story to our XO Chronicles site.
Roger McDonnell