FYI, that last IB flight is operated by IB. I don't know who operates that LHR flight.

I would look out of ORD rather than making it all the way to JFK. If you go from ORD, you will get an IB A330 which is guaranteed to have the new cabin which is quite nice. The AA flight from JFK to LHR is likely a 77W which is another very nice cabin, but there is a lot more chance for equipment swap on that route. The 340 from JFK is most likely the new configuration, but I just got caught out with the old cabin just the other day on the 8:55 flight, so it happens.