[Manolete]

I think these suggestions are on the whole spot on.
I have just one question: What does the Fl. 238883 on the side of the case mean? Does it refer to something that would make sense for this LE watch?
And I have one comment:I think putting WUS-LE or something similar is absolutely a great idea.

Sold case back is a no-brainer.

Non-decorated ETA movement gives us no reason to want to look at the internals.

As for finish, I've never seen a Laco in the flesh, so I'm not exactly sure how the finish looks, but from photos it seems it's a matte finish. Is this correct?

If so, I think the standard finish is appropriate.

As for case back engraving, I like the style of the standard engraving, but on the other hand....

So, I think we should combine the two like this:

• Fl. 23883 engraved on the side of the case
• On the back we should have, in standard Laco style:
  
  Beobachtungsuhr
  Bauart: [See note 1]
  Gerat-Nr. [See note 2]
  Werk-Bez. [ETA]
  Anforderz. [Fl. 238883]
  Hersteller: LACO
  ​

Note 1:
Not sure what to put for type. Maybe WUS-LE or something similar? I don't really have any creative ideas.

Note 2:
For device number, we could either go for X/50, or (I like this second idea better), use some other kind of model number and after the standard engraving have, in an italicised 'handwriting like' script, Nr. X of 50 (as can be seen in the W-SS watch photos, but with 'of 50' appended). Was there a model number or anything attached to the original watch?

 

[Manolete]

Thank you for that excellent summary. In that case, is this ordinance number appropriate for the watch we are honoring?

The FL engraving is an official ordinance number. Aircraft instruments and clocks, for example, had to be built to certain specifications (see the spec sheet that Janne posted) and were then engraved with their specific part (or ordinance) number. All of the other period instruments in my collection have their own FL numbers on them somewhere. In the case of the B-Uhr it was engraved on the side of the case.

 

[Manolete]

This is a great direction we are going in.

 

[Manolete]

I realize this is off topic, as we have yet to get into the details of the dial, but while I am typically partial to sterile dials for this sort of watch, it does make some sense, given the heritage, to have something on the dial. Maybe a WUS-LE and nothing more? That would take the watch away from its heritage without being intrusive.

Some forumers might think the WUS-SA is too close to history.
I feel that the dial should be marked.

 

[Manolete]

"Messbatterie" is an obvious choice for the name of the project (which translates to "test artillery" or "measuring battery"). Anyway, V-rockets, classified tests, misterious reversed numbers - that's all very interesting, it would be nice if the name reflected this somehow.

+1 I like the idea of Messbatterie for the watch.