You won't find one anywhere. Depends as much more on the boat than the engine. A boat magazine with a test on the same or very simliar hull/loading and that engine would be your best shot.
For 150-200 dollars you can put a fuel flow meter in and do your own tests and curves of rpm/fuel consumtion/mpg etc. It's well worth the money if you are into long range running. It will also tell you if your motor suddenly has an problem. If the fuel flow suddenly change at a given speed/rpm somethings wrong.
Third thing- you should never run out of fuel with one. You'll know exactly how much you've burned which means you know exactly how much you have left. :cheers: