It won't make much difference. I can tell you that I have known people running on 5 cylinders who noticed nothing except top end power. This one person bought a boat used and wasn't getting top end power, he starting messing with props only to find out he was running on 5.
If you want to dial it in, start with engine height
One other thing. I'm assuming your using a standard analog engine tachometer. If this instrument is not accurate (and they usually aren't) this will through off your slip calculations and your propping calculations. Using EvDiag is the best way to do these experiments and calculations.
What make, size and weight boat, what top speed, where is the anti-ventilation plate in relation to the bottom of the keel?
"There is never just one thing wrong with a boat";
-- Travis McGee, main character in a book series by John D. McDonald
The factory recommends that a properly trained technician service your Johnson or Evinrude outboard motor. Should you elect to perform repairs yourself, use caution, common sense, and observe safety procedures in the vicinity of flammable liquids, around moving parts, near high-temperature components, and working with electrical or ignition systems.
The information offered here is only general in nature and should not be construed as complete factory approved procedures, techniques, or specifications. Always use the proper service manual for your motor, up-to-date service literature, the correct tools, and have an understanding of how to proceed with troubleshooting and repair methods. If you are unsure or uncomfortable with a procedure, a situation, or a technique, enlist the services of a factory trained technician.