The nose wheel is used ONLY to position the Pushback truck in GSX. It won't have ANY effect on where the plane is positioned by the marshaller.
Missing any better information, GSX will always place the center of the plane in the center of the parking, as defined in the scenery AFCAD.
So, this problem doesn't have anything to do with GSX, it's rather a problem of the current AFCAD supplied with KMEM, which needs some of the cargo positions to be adjusted for larger planes.