Spera Chronograph information request

Hi, I have a Spera chronograph that I have been unable to find any real information on. My knowledge of watches is pretty limited and with the expertise on this forum i am hoping to fill in some gaps. My searches have only revealed that Spera originated in Tramelan outside Geneva, possibly from around 1920. I have seen a few examples of mid fifties Spera posters and a smattering of basic 2/3 hand watches and some 60/70's vintage 2 register chronographs.

The watch appears to be in good working condition and appearance, ~36mm case size ex crown. The sweep hand snaps back to 12 nicely. I seem to recall that I had the watch serviced/crystal replaced and put it on a leather band around 15 years ago. The only references I have come across in my searches refer to Landeron movements, but a watchmaker who opened the case said he thought it was a Le mania movement.
If possible, I would like to know the likely vintage, movement type and any general comments and feedback. I wouldn't mind some idea of the value if someone has an idea.
I have included below some pics of the watch, thanks in anticipation.

Beautiful original piece! Due to the arrowhead markers I would date it end 1950s. The movement is a rather rare bird, the Landeron 349! If you look closely, you can see the number under the balance wheel 😉

The case will be either gold plated or gold filled.

Spera is a brand of some interest to the Dutch collectors, as they made some Koninklijke Marine (KM) watches back in the day.

Yup, rare movement in there. Differentiation between this and and a Lemania 1873 (or Omega Cal 861) is the cam-lever setup. Apart from relumed hands, it looks great!