We have been one of the pioneers for the Aatoncode system.
It used to be visible, man-readable numbers plus barcodes on film and man-readable numbers printed on white SEPMAG stock. It then evolved to telecine via Keylink putting man-readable numbers in the image plus machine readable timecode in 3-line modified VITC on Betacam SP or Digital.
Since everyone is now receiving rushes on fileformats, either we sync the timecoded audio to the man-readable audiotimecode on the picture (in case of rushes), or some users use an timecoded clapperboard.
The good old clapperboard still works with a crystal controlled camera. A digital audio recorder should be sufficiently stable to allow lip-sync with the clapperboard.
I think you can find a good selfblimped camera with crystal controlled motor for less than doing a DIY hack on a noisy old camera.