Re: shifting
Depends on your definition of hard shifting.
Because the gears engage with drive dogs, it is normal to hear a "clunk" as you put it into gear. If it is engaging harsher or noticably louder than normal, the idle speed may be too high. I'm not sure about the 5 cylinder 150 but the 4 cylinder engines are supposed to idle at 700 RPM or so IN GEAR IN THE WATER. The five cylinder 150 having an extra cylinder and torque could probably get away a little slower--but not much. Remember that most auto engines idle up around 600 rpm and that's with no load.