Fzr 500....... seems to be that most were destined for the European market although a few appear in Oz/NZ.
Was this a horsepower restriction perhaps ?
It appears to be a lesser capacity 600 (3HE) rather than a larger capacity 400 .
Anyway,back to your question;
I would go for the 06/07 R6 shock.
There are usually lots on German Ebay in very good condition and at a good price.(its where mine come from)
You need 138mm center dogbones to keep the geometry the same as original.(Stig on here does them as does Kayla @
http://www.projection-components.co.uk/.
I have not listed US members who also do the suspension links as you are in Austria.( you can decide if shipping is viable)
Also required are spacers for the top mount (washers will suffice at a pinch) either side of the shock mount which is thinner.
I drilled the top shock bush out to utilize the original bolt rather than use stepped spacers and a smaller dia bolt.
There is an abundance of write-ups on the installation.
The R6 shock is a known upgrade and highly recommended/easily accomplished.
I have no experience of the Fz1 (Fazer 1000) shock in a FZR but have fitted the R6 unit to my 600 3HE and to four of my 400's.

Sent from my keyboard using the English language not some teen text shite from a fooking phone.