Questions come up regularly about recommended sprocket changes and the required chain lengths for superbikes. Here's my recommendations for general street and track use.
There's a "sweet spot" - around 4,600 RPM @120Km/hr in 6th gear for liter displacement superbikes, a little higher for 74X's. Obviously, faster tracks will require rear sprockets with fewer teeth, slower tracks more teeth (and possibly longer chains.)
I strongly recommended NOT changing the stock front sprocket or chain size for safety reasons. Just my opinion.