Hi Hatstand and welcome here!
Your Seamaster looks legit as far as I can see. Seems like a reference number 14701.
You have some small issues (crown replaced, lume loss / degeneration, second hand seem to be a bit too short) but overall the watch seems in good conditon.
I can't comment on the black material but the caseback should look like that:
https://omegaforums.net/threads/omega-seamaster-automatic-14701-1960s-freshly-serviced.21488/
Is the watch running properly?
If you intend to wear it regularly you should think about a service which could be necessary.
Depending on your location you could get some recommendations here on the forum.
All the best!
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