In reply to @brickford
for the 763
It's in my opinion normal that I take the side on the inside since the saddle is placed on the tube
and in terms of the width of the saddle it is required 40
with a 165
so I think I'm on target ;-)
The basic ferrule is 763 in outer diameter and 8mm thick
The penetrating tap (which is also a ferrule) is 273 mm in outer diameter.
The famous reinforcement seat is therefore in an inner diameter of 273 mm, necessarily it has a width of 40mm and a thickness of 8mm.
See attached image