What do you expect the prop to do for your wake?
Increasing the number of blades and/or increasing the diameter of the prop will increase its "grip" on the water, reducing slipage. It also increases drag and makes the prop harder to turn. If you are experiencing problems with cavitation this will help. If you feel that you don't have enough horsepower to start with, this will only make things worse.
Decreasing the pitch on the prop is like shifting your car down to a lower gear. It will give you more torque at the lower speeds, but you won't be able to go as fast without over revving the engine. If the boat struggles to pull you up then a lower pitch prop will help. Your dad may not appreciate the fact that he can't cruise at the same speed he used to, however.
If what you really want is a bigger wake, the prop is going to help.