RE: how to get the most power
If I am not mistaken. The motor is a 1/2 crank, reed valved motor with a forward facing exhaust (like the old Mac motors).
There really is a limited amount you can do to it. Make too much speed/power and you will loose the rod. Hard to put any kind of tuned pipe on it as the port is forward facing.
If your determined to use it then just aim to get her running reliably. Run regular gas in her with 8oz of good oil/gallon. Run it a hint rich as air cooled motors will get hot in a boat and if you lean it to make power it wont last long.