The last conversion I did I had to groove the prop hub with a file.
Not an easy task, I worked on the hub and on the key till my fingers hurt.

What I did was ... I bought some of that apoxy putty with metal in it.
Put it where the key was suppose to be and installed the prop hub.

I waited 5 minutes and pulled it apart.
Everything looked good.
I cleaned it up and put in another dab of putty and everything is still working good.