Lisnagon appears to be in the parish of Kells in Co. Meath. Birth/baptism rcds for this parish begin in 1791.
I searched the Irish Family History Foundation's database. It contains 12,000,000 surviving rcds for abt 65% of Irish counties. Rcds B4 1840 are increasingly sparse, B4 1800 rare. I only search the existing database.
In Co. Meath for the surname Tighe (+variants), there are 289 B and 142 M rcds. For the surname Smith, the figures are 9,317 and 3,255 respectively. With difficulty, B & M figures can be found for each Meath parish. Will leave this task to you.
Google the Foundation's name to lead you to this database. Pls post your search results to my genforum msg.