rpm range of 85 70horse yamaha

[Flakey]

I need to find the rpm range of an 85 model 70 horse so i can determine if i can change props to gain a little speed on the top end and lower rpms. it runs 6000 rpm at top speed and i feel this is too much. it currently has a 17 pitch prop. any suggestions would be greatly apprecited

[boats.net]

4500-5500 rpm's