Hi Ger As you no doubt know the standardisation of Irish placenames was only completed in the 1830s as part of the Ordinance Survey. This led to the drop of a significant number of traditional names for places. One useful place to consult for help with place names is the logainm website. Here is a link to what it says for Killycoghill and this gives a map link as well.
http://www.logainm.ie/en/40603?s=Killycoghill
Jill
