Looking for relatives of Patrick Murphy (born 1840) and Catherine Hennessy married in Kilbride, Cavan 20/10/1866

Am trying to determine if this couple are my GGGG's. Tracing backwards from my father, has led to an Irish family living in Brooklyn when a son, William, is born in 1868. The names and rough DOB's on what records we've been able to find in US -- circumstantially match this couple that we stumbled across in IRE but so far we've not found a definitive link.

I'm curious if any record of this couple exists in IRE after their wedding in 1866. Where should I look?

Also what would be the typical leaving port for emigrants from this area ofCavan between 1866-68?