I tried to find the crystal number for you, but I couldn't find my catalog. If you can find a .pdf online for the GS Catalog, it may be listed there, but TV shapes are always very difficult to source.

Sorry can't be of help. The crowns are unclear. I'd imagine 5.0-5.5mm is typical.

You're welcome; I have those as used parts if Perrin doesn't.

The parts in question should be the same between 497 or 497/1....maybe ask Perrin why they'd be different, but I expect them to be the same.

This is the TV shaped case?

1951, 1953, 1953, 1954, 1954, 1956

That is when they were produced as a movement, which could be cased later.

I tend to agree with the above post. Also no indication of SWISS or T on the original post on the watch dial?

You can never say never with the Swiss, but 424 normally has no date function.
I can't say I've seen that case either!

Several manufacturers made that style of watch in the 1930s. I don't think you'll find much more information on it.

Something doesn't add up here. The case is 200k and the movement is 26k?

Usually, the movement number is HIGHER than the case number.

SWISS T would indicate tritium, which wasn't commonly used until the 1960s.

So no, it would not be original to the watch.