Dear Jeff
Welcome to Ireland Ireland Out!
Yes, the years of birth do seem a little strange. One of the other issues with this situation is that RC records for the parish of Ballysadare and Kilvarnet do not begin until 1842 for baptisms and 1858 for marriages. This means that before that time there will be no baptism, marriage or death records for anyone in that parish and that is why you have had no further luck on the sites you mention above. If your ancestor was Church of Ireland, records there too begin in 1845 and are therefore of no use to you for that earlier period.
The only other sources I can think of that would be of potential use would be things like the Encumbered Estates Records in the National Archives, Dublin. Even though these start in the 1850-60s they sometimes refer to earlier rental details for those who rented land later sold off. Unfortunately these are not available online. There are also tenants listed on the O'Hara Estate covering Ballysodare in the National Library of Ireland, again though, not online.
You may have to consider whether hiring a researcher for a short time would be of any assistance to you or perhaps add this as part of a potential planned visit to Ireland.
Let me know what you think
Clare Doyle
Genealogy Support.