When I lived at Villawood 1954 there was a place we called 'the aero dump' at Leightonfield [5minutes on my pushy]. It was a paddock full of old ww2 'planes being slowly scrapmetaled and they let us wander around the junk.When I started with bikes with engines I remembered seeing a lot of dials out of magnetic compasses so I went and grabbed a dozen or so for timing discs. They were made of brass and engraved in 1,5,&10 degree points. They were about 10 inches dia. and just needed a 3/4" hole in the centre to fit the end of my Matcho crankshaft.
Perfect! Trouble is I gave them all away over the years except one and now its lost!.
Maybe some of you old farts from MDMCC might still have one.
cheers pancho.