I have a 98 four winns horizon 180 rs 2480 lbs with a 4.3 gl 190hp 4600rpm and a sx outdrive with 1,79 gears and a 18 degrees dead rise
it has a vortex MI Wheel 14.25 x 21 3 blade on it now.
I think a 4.3 190 should be at the high 40s @ 4800.with a 21" prop.
Its not unusual for a 4.3 to go close to 50.I think a 3.0 in a boat like yours would run close to 40
with a 21" but may struggle for hole shot.
You may want to confirm your setup is up to par.A 4 blade isn't the choice for more speed.
A 19" 4 blade should improve holes shot maintain speed better at reduced throttle may respond better around the dock.
It might maintain your present speed.