LJ50
I would imagine that a B777 would have to use stand 55, like the qantas B747 uses, due to taxiway restrictions.
As for the AF, it also uses 48, 49 other 50's too, though majority of the time it goes on 44L. Skipness is quite correct, a B747 is largest for stand 44, the stand layout has changed recently since an a330 was on the same stand :-)
I have to say i would be surprised to see Cathay in T3, either T1 or T2 would be more suitable, as what happened recently with the diversions