I saw B-HOO (74J with NBC and large J cabin) servicing the HKG-JFK route last Wednesday.

JFK is one of CX premium routes, so you will likely to get the NBC 99% of the time. Of course, there will always be last minute substitute.

LAX is the other premium market. They also get the 74J much, and with Airbus A340-600 returning to LAX late September, there will be one flight guaranteed to have NBC.

Carfield

PS. JFK is nice, but only wish that CX can use its own staff in the future and finally launches the nonstop JFK-HKG flight.