Re: 1990 4.3 2050, what prop??
When you install a new - or used - prop on your boat it doesn't matter how fast you usually go. You need to match the right prop that will turn the full factory rated highest rpm's on your motor. Since there are no transmissions ( just gear boxes ) on boats your prop acts as the tranny. Too high of a pitch and your motor will strain - not good. Too low of a pitch and she will over rev - not good. You need to find one that falls in between.
Hoped you followed that. Needless to say the best procedure would be to give your local dealer a call and get their recommendations for size and pitch.
Or - you could call Bayliner and ask them what they installed from the factory. ( 877-861-6494 ) Have your HIN - they will need it to help you.