If you get us the information from a lightly loaded wot test run. rpm and gps speed.
If the boat is full dress with floor,deluxe seats ,windshield gear,trolling motor?
Weight is likely about 1000 lbs A little basic probably 600 or 700.
The motor needs a prop that allows it to operate within its rpm range 4500-5500.
The final size will depend on your typical load and activities.
Some boaters use more than one prop.