omc 2 hole, major horsepower, minor motors, carbs and exhaust is the cheapest way. you might set your time up, it seems like you have the compression numbers about right. those motors can run comfortably up to about 205# without worry, some race motas are above 225, i wouldnt try that right now. you can finger port one and get a little bit more out of it. just a little food for thought.