Right RPM's for a early 90's Evinrude

I just got an early 90's 50 hp evinrude put on my '89 deep v 17ft bass tracker. My question is at full throttle it runs about 6500 RPM's. I looked around for some info and the only thing I could find was someone saying outboards should not run over 5500 RPM's. So when I run it I keep it at about 5000-5500 RPM's. Can anyone tell me what is the correct RPM's to run this motor at and if I need a different pitch on the prop (don't know what pitch is on it now) Thanks

Pretty sure that the power pack has a rev limiter and won't let the motor turn over about 5900 , so I would say your tach is reading wrong. I would check the rpm's to a known good tach or an inductive meter to read the rpm's and compare. , and yes 5000-5500 is the correct rpm's