I haven't done a full front end swap, so can't comment 100% what's involved.
I can point you to this thread though!
http://www.gasgasrider.org/forum/showthread.php?t=14592
and this one too.
http://www.gasgasrider.org/forum/sho...t=12745&page=3
You'd have to check the offsets for that particular Yamaha model. The GG uses a 22mm triple, and 35mm lug offset if I recall correctly. YZ 2T uses 25mm triple and 32mm lug, so same same. I reduced total offset by 3mm with my fitment, and notice the difference in terms of force required to steer the bike, but don't find it bad at all (but that's on a 13 chassis too).