This does
not sound like a simple job to do (tho not entirely impossible, just a lot of hassle and expense).Are FZ8 forks the same diameters as the FZ1 forks (internals are almost certainly different but that's irrelevant). If so, it's the FZ1 top & bottom yokes you'll need. Have a look at Mike / Falcon's R1 front fork conversion guide for the FZS1000.
http://fazer1000.yuku.com/topic/3408/R1-Fork-Conversion-Guide#.VOCl5iyM69c Different bike I know but the FZS600 and FZS1000 steering stems are the same so you'll need to follow the same sort of procedure.
The FZS600 front wheel almost certainly won't suit the FZ8 / FZ1 forks, different diameter spindles and bearings... and then there's the speedo drive problem.
It's almost unique to the FZS600. Unless you do the Muddybuddy speedo drive conversion; in which case you could keep the standard clock unit & run an FZ8 front wheel to match the forks. but then, you'd be running a 120 front tyre instead of 110... more issues to consider!
I ran RWU R6 front forks on my FZS600 for a while, but emulators and springs in the standard forks were the best bang-for-the-buck option.