No, McCallum`s reach advantage and ability to slip would be a big problem for GGG, it would be a close fight.
all your posts are like you are stuck in the 80s and 90s, and you have a massive bias for fighters from that era.
No, Graham didn`t throw enough jabs, his reach would have been a problem for GGG though, I mention middleweight because McCallum was better at 154.
GGG wasn`t active enough with his lead hand despite jabbing a lot he didn`t feint much with his lead hand, he didn`t keep his opponents guesing enough, McCallum was too smooth for GGG.
Murata had a longer reach than McCallum and Golovkin had zero problems. In fact GGG has had the shorter reach than his opponent in virtually all his fights and he's coped just fine.