That is a Dennison cased model, assembled in Handsworth Birmingham using an imported Swiss dial and movement. The 4337 is a Dennison number not Omega which is why you may be finding it difficult to find a match. The dial looks correct for the style of case but may have seen some work previously, the Seamaster text looks a little off but it is very dirty so it may in fact be fully original just hidden under grime. I agree with your estimation of date, 16.2m would be around 1958.
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