80's 150, 175, 200 mercs are good picks. So is the 130 yamaha.
I can plane below 12mph with my seafari now and I'm averaging usually better than 3.5mpg at a 30+ mph cruise (even at 35mph). 175/200 2.4L weigh 360lbs and the 135/150 2.0L is closer to 380.
looks like the factory powered the 20 with 2 3 cylinder omc's at one time, but I prefer 1 big motor and a kicker.
