Talking about 777s at LBA, if anyone remembers the GE90 rollback issue some years ago EK and others were using the aircraft fitted with those engines at full takeoff thrust for a short period.
Forget LBA, a 773ER could have used London City. They were leaping in the air when not using the systems to derate them based on payload and available concrete.
PIA have some bog standard 777s and also the 772LR with the big GE90s so if their scheduling permits then a 772LR would be the ideal plane for the job. Plenty of thrust and reverser action available to compensate for LBA's short runway. The aircraft uses runway if it's available, but when it isn't then they have considerable flexibility to crank up the power. These two frames (BGY and BGZ) regularly turn up on less taxing duty such as the PK701/2 at MAN so slotting them into LBA may be possible if the pavement loading isn't a problem.