FULL, FULL AND FULL I would suggest. Aer Lingus flight 105 has been running completely overbooked in Business Class of late, ever since delta scrapped their flight with it's massive bizelite cabin. So much so, I heard that usually the have to downgrade full-fare business passengers and offer them compensation. If you have a confirmed reservation in economy you will be allright, but if your looking for a freebie upgrade you stand no chance whatsoever, unless of course you're willing to dress up as someone famous such as the pope, which I would doubt very much.
Yeah it's a shame that flight used to be great, now the high loads are killing it. Why don't you fly from Shannon instead, i believe the aircraft on the SNN-JFK run at the moment is a large-business class configured A330-300.