Mercruiser service manual says for the 165hp engine, with a RPM spec of 3900-4300 I'd want a 16", 11 pitch, 3 bladed prop.
Under the "approx boat length" I fall under "houseboat", and it is a houseboat. Next column is speed range, listing 10-18mph
Row above is 30'+ 16-24mph, (I'm probably 36ft...