Looking for John T. O'Sullivan, born 1637

Hello,

I'm an Irish-American who has traced my roots to Kerry via ancestry.com. My father passed away recently and we want to spread his ashes back in Ireland this spring, and would like to visit where our ancestors are from. I was able to trace his line back to a John T. Sullivan in Co. Kerry, born 1637 and died in the States 1698. Any advice on how to research further would be very much appreciated.

-Amy