OK, so no joy so far. Possibilities:
1) New Ross extends across the river (not much, but a little). The Kilkenny side is not in the parish of New Ross, but Rosbercon. There is a gap in the Rosbercon registers around 1833.
2). Mistranscriptions. I have seen some bad ones already. Ebitt, etc.
3).Different variant of the name. Examples McKevitt, Kevitt, McEvatt, etc.