I am kinda new to boating. I have a 24' pontoon.... starcraft Orion 241 i/o with 3.0 mercruiser alpha 1 gen 2 drive. Bad motor (dropped valve and ruined block) and have been toying around with a diesel. About 100# heavier but I figure I can relocate 30 gal fuel tank and compensate for the extra weight in back. We are not going dor speed but something just for pudding around the lake in TN. No need to go over 20-25ish mph. Any thoughts? I am looking at 105 HP 220 torque GM engine. 3200 rpm sustainable red lines at 4000. Any input?