Sounds like the generator would be the easiest to change, but I'm not familiar with your generator. Speed is going to be a function of pulley diameter, both the driver at the crank and the driven pulley at the water pump. So assuming the crank pulley is original, if the pulley at the water pump is the same diameter as the original 235 water pump, it will be turning at the same speed as the 235 pump.
Anyway, it is a pretty easy math problem to find out what speed the water pump will be turning for any given RPM of the engine.
If you mark a place on each pulley, and turn the engine over one revolution, make note of how many times the water pump pully rotates or what fraction of a rotation. You can use an old fashion protractor to help you out. Then you will have a ratio in degrees. So as an example, if the crank turns 360 degrees and drives the water pump 720 degrees this gives you a ratio of 1 to 2. So if your engine is turning at 1000 RPM the water pump will be turning at 2000 RPM. If the crank turns 360 and the waterpump turns 180, then you have a ratio of 1 to .5. So if your engine is turning at 1000 RPM, the Water pump will turn at 500 RPM.
Just a simple example.
Kurt
