Try getting a 77W to JFK with a full load from LBA.
If you could...you'd make a fortune at RR.
Er...77W has an exclusive GE offering.
A300's can operate, probably at the margins of economically, B777's cant.
PIA don't fly A300s and the B777 is a more powerful beast.
The real question is whether they are interested in maintaining the US routes ex MAN as with the 77L they no longer need the stop.
Air India has just pulled BHX-YYZ as well. We shall see.