I hear you about keeping it stock, and I think you'll still be happy with the stock fizzer (looks very clean and well kept, by the way), especially if you have another bike you're modding. I love the classic look of the FZR600, and I get stares and compliments every time I take her out. I personally only have one bike, so I also mod mine a bit, but I try to keep it fairly stock appearing (if you familiar with the term "sleeper," you'll know what I mean). No R6 tail for me.
I'd say if it runs fine, just do regular maintenance and leave it alone.

Enjoy riding it, and ride it every chance you get. It's too easy to get too carried away with too many projects, and if you're not careful you'll find yourself in my predicament...wanting to ride the bike but having 4 or 5 major mechanical projects that needed to be done yesterday.
