Looking for information on John C. Buckley, born 1809-1810

I'm quite certain my 3X Great Grandfather was born in Kilmeen parish around 1809 or 1810.  His name was John C. Buckley.  he emigrated to the US in 1839.  The Irish Genealogy site says baptismal records do not go back as far as 1809 for that location.  I found evidence that he may have been baptised at the Church of The Emmaculate Conception in Boherbue but his badly worn gravestone (in Illinois) says he was born in a parish that begins with KIL and I can't quite make out the rest but Kilmeen could very well be what it says, due to the length of the parish name inscribed on the stone.  It will be several months before I can make a trip back to the stone to get a rubbing, hoping it reveals more.

From what I read, people in Ireland did not leave due to the potato famine until the mid to late 1840s...  I'm wondering what series of events might have been going on politically and otherwise that would have caused John Buckley to leave in 1939, other than poverty.

He did go on to be a wealthy farmer in upstate Illinois, Galena area.

Is Buckley a common name in this area?  Any light that can be shined on my ancestor would be greatly appreciated.

Thank you,

Paula Steffgen Pasterski