| stock fitting is 241mm, i think, from the top of the machined face on the bottom yoke to the top of the fork leg (spring cap).
The rings are "irrelevant" due to the relative postion of the head race nut. In reality, it's a fraction of a mm but that's how to set the position from scratch.
I think that the top yoke sits with the clamp slot just lining up with the third ring?? | 
Threaded Mode