I remember reading somewhere the R1 forks are like 5mm shorter, not sure if that would have any affect on just putting the internals in yours.
Down load the R1 manual and go through the suspension section, then go through your FZ8 manual. See if there are different torque settings, difference sequence of events for removal or installation. If everything matches up, and I had the internals just sitting in the garage, you know I would be all about trying to get them in those stock fork tubes.
DJ