Is 90 hp adequate for 1967 19'6" bowrider?

[doughert0]

I have a 1967 seacraft bowrider, 19'6", 1150 lbs empty weight. I have been running 115 hp but the 2009 motors are 75 to 100 lbs heavier than my 1999 Johnson special, and have a much higher profile.

Seems like years ago folks were regularly running 90 hp engines on this hull. Anyone know whether a 90 would be adequate. I fish in salt water, and if I top out at 20 kts I'm happy - the 115 gives me about 25. Most times it's too rough to run that fast. I sometimes have four adults in the boat, and ususally start out with 42 gallons of gas. Normal operating weight would be about 2000-2200 lbs.

Any thoughts?