Well if he is your friend as you say, then he should have no issue letting you try it first. You might not be able to spin it with a weenie motor like a 305. But this all hinges on the weight of your rig. Find a local prop shop or a dealer that will have props to test. You motor will need to run at it's top RPM, what ever that is for that motor, maybe 5200-5400? And the only way to know what that 23 will do or any prop for that mater is to put it on. Get a baseline on the prop you have now and go from there. IE: Do you want to ski, maybe two skiers???