I have one of the one piece crank cases & shrouds. So far I have all of the metal cut off & just have to do the final grinding to make it look nice. The propeller I plan on using is a Classic Series 18x6. The hub portion is 1 9/16" diameter. What diameter would you machine the hub adaptor to, where it mates to the back of the prop?

the one i bought is 1 1\16 at the fly wheel 1 1\4 at the prop & i 3\4 long
fj5