We extend to you a cordial "WELCOME ABOARD !" Come on in, make yourself at home, we are a friendly group of enthusiasts, and we also appreciate the classic Chris Craft Roamer, Corsair, and Lancer boats too , as they are all on the same family tree and share much in common !
Did you notice on my photo that the keyway did not extend through the threads? Another benefit from the CNC process.
I suppose if you have a spare prop you could get pretty close by doing a mock-up at your boat, measuring the clearance from back of prop hub to the strut facing, measuring the actual depth of the internal propeller bore itself, and then leaving some for the thread too. There is some degree of adjustability at the CC prop shaft hub itself, where it mates up to the motor hub. I know because mine was held in place with a couple set screws that would not hold the entire thrust of the shaft and it wanted to work its way forward. It walked forward enough that the propeller hub actually came into contact with the backside of the strut and it wore a little metal off the propeller itself just on the hub. As a result I added some stainless steel washers inside my hub connection at the transmission to take any thrust, so the set screws would not be asked to do a job like that.