I had to abandon my first attempt at this as I have machined the 10 mm spigot too small. Also, the piece of stock I started with was not long enough for me to machine the larger spigot on the hub end. So I will get some more stock next I'm in town.
The 10mm spigot also only needs to be short, perhaps 6 or 8 mm. I will make up a washer with 10mm spigot through which the 5 mm retaining screw will go through, to centre it in the prop centre hole while drilling the six retaining screw holes.