Hi Austin,
The information that you have on your ancestor in America is a super place to start!
The information on County Louth is important to know as before 1864 records are kept at genealogical centres based on the County. Please have a look at
Lough County Council pages for research information and services that are available.
Would you have any birth, marriage and death certificates that you can use to confirm John's Irish background? These types of documents are extremely worthwhile when tracing family history.
With some additional information, a trip over to see us in June would be a lovely way to see the places where your ancestors lived prior to leaving to start a new life overseas.
Speak soon,