I think if you get a 61" bucket, you'll discover that you now also have a big clumsy thing sticking out the front of the tractor too. It will make maneuvering in tight quarters even worse. And knowing a little bit about that tractor, I wouldn't want a bigger bucket unless you only handle light materials -- if you take a healthy scoop of gravel/etc, it's probably going to be too much.
If anything, the box blade might be too big, although it is probably only sticking out about 4-5" on each side. A 54" might have been a better match, but if the 60" box is really only sticking out 4-5" each side, that should not be a big problem. If you're getting close enough to something to hook the box, then you may have already risked damaging tire sidewalls by that point.
Any advantage of a wider box -- letting you get close in to stuff on the side, is going to be outweighed if you go with a wider bucket. At that point I think you now have multiple disadvantages.