I don’t know the answer to your question but DO know that any smiths chronometric can have the internals altered to give correct mph etc, also a dial can be “printed” to have the correct part number if you want to go to those lengths to be correct.
In other words the part number on the dial being “wrong” can be corrected easily by an expert.
The physically visible variables in spec include bezel type, trip meter (or not) and its location, provision for bulb (or not) etc.
