Chris, I would check Allparts or Gotoh. Tokai screws are smaller in diameter than the original 50 ones (Gil yaron can supply some set similar to them).
I can confirm the ones from MusicElectronics in USA are longer and the ones from Thonman Germany are longer than MusicElectronics.Can order small ones and putb them in all positions.
I have put the ones from MusicElectronics with sucess in a 80s Tokai recently.
http://www.guitarelectronics.com/category/parts___hardware.screws___springs/
http://www.guitarelectronics.com/product/SCHB3S-24/Short-Humbucker-Mounting-Ring-Screws-Nickel.html
http://www.allparts.uk.com/collections/pickup-surround-screws
http://www.thomann.de/es/thomann_humbuckerframe_screw_set_n_ni.htm
http://www.thomann.de/es/thomann_humbuckerframe_screw_set_b_ni.htm