Now that GV has discovered amazing photos showing Seppi wearing a white Autavia with MH bezel, Automatic writing, and early case,
i did not want to remain with the doubt of having the 'wrong' Siffert's Autavia, so here are both my Siffert's Sifferts:

Interesting to notice the position of the 'Automatic Chronograph' writing:
in the standard 1163T dials it is placed between the black register, but in this very early version it's very close to the date window.
Exactly like in the watch worn by Jo!