Owen,
I make indexing systems for woodlathes. Contact me through my website
and maybe I can help you out with a custom indexing plate if you wish.
Our stock plate for either 1 inch spindles or 3/4 inch spindles have
two rows of indexing holes. The first row of 72 holes are 5 degrees
apart and the second row of 20 holes are 18 degrees apart.
Tim Q
"A-LEE-SAM"
http://alisam.com/