ORIGINAL: invertmast
Or you could just buy the $20/30 prop drill jig that nearly every manufacturer has for their engines now.
It still amazes me how people in this hobby will spend weeks and $50+ trying to make something ''easier'' by redesigning a known working design only to have it fail, when there is already an easier way of doing so.
The prop jig is fine and useful for drilling the holes in the prop, and typically that's fine for a single bolt spinner set up where the spinner can sit anywhere, but it doesn't align the prop to the prepositioned perimeter holes in the spinner's back plate.