Omega Watch Identification

Hello. The Omega watch in the photo belonged to my late grandfather. He passed away over 40 years ago, but I only recently found out about the existence of this watch.
To be honest, I don't know much about watches, so I searched omegawatches.com/vintage-watches, eBay, and a few other sites to find the model and year of this watch, but I couldn't find anything similar.
I’m attaching photos of the front and back. The back seems a bit mismatched with the model, as if it were added later. But as I said, I’m not very knowledgeable about watches.
Could you help me find information about the model? Thank you in advance.

Thanks for the info! I saw similar Omega watch models, but I couldn't find one with the same dial.

You must hover the image to and scroll on sides for back side picture. If not working here is the link.

I want to open it and look inside. Since I am unfamiliar with the watch, I have been studying the sources on this subject on the internet for a while. When I compare the back of the watch I have with the Omega watches in these sources, it looks too plain and flat cover, like a tin. It left me with the impression that it might not be original. What do you think?

If is all good, the inscriptions are on the inside of the back. A watchmaker will open it in a minute, unless you have done it before you risk to mark badly the metal.

It was quite common that watches with gold plated case would have steel backs, as the friction and acid skin would corrode the plating.