Fortunately Jim does have a spare prop. I didn't realize that it would be difficult to find one for such an old boat. I will remind him that he might want to keep it on the boat for emergencies.
I will review the technical information of your post with Jim.
Thanks for taking the time to post. I really enjoy everything that I have learned from this forum.
Has he tryed it yet on the boat at full throttle, to check for vibrations/balance? If not, encourage him to try it. That way if it is off a little he can get it to a prop shop to get it balanced so it is ready for use.Some people just want to say"it'll be all right", but when it's needed, then they find out it is trying to shake the motor apart. Have him put it on and run it in the water, not just on the trailer, makes a big difference.