1989 20 sf with suzuki 140 performance

[bibijawa]

Im finally going to repower this year. I have a 1989 20 sf with a 2001 150 hpdi. I cruise at 30 mph at just under 4000 rpm. Im normally loaded heavy with 80 lbs of ice in fishbox, 40 lbs of frozen chum, 53 gallons of fuel, 20 gallons in the livewell, tons of rods and gear and 2 other passengers. I'm happy with the way the 150 pushes the boat. Now, if I switch to a Suzuki 140 will i loose alot in my cruise speed? Will get better mpg? Please help me, I really want the 140 but will get the 150 suzuki if the 140 is not enough for my usual heavy loads.