Seems like a popular mod
Anyway it is finally done and advise would be: don't bother.
In my case it was not a mod, but fix, as I have bought FZ1 with bent forks unfortunately. Only noticed it when brought bike for a forks service.
Being on a budget, best cheapest fix was a goal. Finally i have found 2002 R1 forks, as i thought they will be an easy swap, i could keep FZ1 brake calipers, rotors. It wasn't. You need a smaller rotors, R1 axle, and so on. Finally end up just using R1 forks outer and inner tubes with FZ1 internals. It was cheaper than getting replacement parts or finding used FZ1 forks, which is hard to find as it turned out.
Final result is good, bike back on the road.
