@erikt
Do you mean Technics SL1200 or SL1200 MK2?
I'm talking about SL1200 mk2, the earlier 1200 comes with different tonearm, i have never tried.
So the 52mm cartridge overhang alingment tool that comes with 1200 mk2 tonearm is not Stevenson geometry for sure!
I know this because i use Stevenson on this tonearm with stock technics headshell (gold version) with my grado cartridges.
My tool is Dr. Feickert alignment which is presicion device to set up the carts to Stevenson, Baerwald or Lofgren. When my cartridge set to Stevenson the overhang is not 52mm, but a bit more than 53mm. It's easy to check by inserting the cart/shell back to Technics plastic tool to make sure the diamond is not on the 52mm mark (where it should be according to technics tool), but 1.2mm forward and a little bit twisted toward the center on the platter.