I would dearly love to rehouse my RR Chronometre in it's original S/S case. But I have no idea what the dimensions of an original crown are. The only detail I have from pics. is that the U logo was on a central domed section rather than on a curved top that started from the edge.
Railrouter Chronometre
Movement numbered 9298
Also repeated on outer caseback
No Ref. or Ser. No. Just 12501/1 on outer caseback.
Logo on inside caseback