is it def an FZ? or FZR steel as opposed to alloy framed.
£1k is at the top end of the FZ range, it would have to be MOT'd and running sweet for that.
I would offer him £500 and get to £800 if your confdent in cleaning carbs. That's if the bike hasn't been running for a while.
there's an article in December's Practicle sports bike on the FZ and they promote an 80's race foemulae which the top 10 bikes are FZ's