Gotta love fuel injection.
I still haven't broken 60 MPG in either of my bikes, but that will likely change as I just synchronized the carbs on both of them, and put leaner jets in the VFR 400. That fuel injection must help a lot, carbed ninja 250s seem to struggle to break 60 mpg on fuelly.
Feel like you can go taller on those sprockets? The JT sprockets catalog lists your stock gearing as 14/42, with down to a 38T rear sprocket available. I believe there are speed correction devices for bikes, have you looked into one?