I have to agree outboard jets are definately not the way to go. Also for packing anykind of weight I would agree a 350 is the minimum in a boat 19-21 feet. I have been in a 19ft northriver with a 305 and it is fine with a couple of guys but when you load it down with gear it just doesn't have the power. A 383 is a pretty good motor weighs less than a bigblock but gives out some pretty good power. As for a diesel I think you would need to run your boat a helluva lot to make up for the extra purchase cost and matinence cost will also be higher for a diesel.