There are certainly problems but it can be done. The 550 triple clamp has a different offset which will definitely affect handling, I think it will make it harder to turn rather than more twitchy but i'm not sure. If you can find an old 450 triple tree setup the geometry is the same and the spacing is right for the 550 forks and wheel I have been told. The steering stems are both too long, you have to remove the 550/450 stem and weld in a 350/400 stem. Not really a big hassle, you just grind the welds off the bottom of the trees and press the stems out, then reweld the proper stem in the tree you want. The diameters are the same.
Also the old 450 forks are supposed to be the ones to use, the damping unit is better than the 350/400 or 550 ones. Single disc though.
