Apart from the 14 twin-track and one centre-line positions remaining on the main-deck, as well as lower-decks able to hold around 50 tons, yes, it's quite full.
There's also the not unimportant matter of the 777F main-deck door being 5 centimeters higher and 41 centimeters wider than that of a 747F to take into consideration. I have my doubts a 747F can take a GE90-115, whereas the picture above clearly shows a 777F can. Even if you can get a -115B through the door of a 747, you would have to load it centre-line anyway.