I have an FZ II: the model before the FZR. The engine is basically the same except that the FZR’s is liquid cooled. The FZR also has a back disc. I got the FZ instead because I preferred the slightly more upright riding position.
It was ten years old when I got it (for 15,000NT) but since then I have put maybe 35-40,000NT into it: complete engine rebuild, fork and front brake renovation, new back shock, starter motor and other bits and bobs, a gel saddle, decent tyres and many other things.
It handles very well but is underpowered. Resale value is probably nothing like the money I have put into it.
So I would ask you, do you really love the bike and want to continue using it for a couple of years? If not, it might not be worth putting money into serious improvements and you might be better to either fix it up just enough to keep it running OK or sell it and get something else.