Need some help / Advice Vintage 1950s or 60's Seamaster 18k

Hi all,
I'm new to the site and a new collector I guess.
My Grandfather passed down this watch to me which he purchased in New York in 1963 from his jeweller.
Fully working and has a great sound to it. Can any members help me identify the vintage, model, etc?
There is very little wear on the watch other than the strap, it has never been polished. Some small scratches on the back but the crystal is in great condition and functions normally for a mechanical winder.
Case measures 35mm to the crown which is marked with the Omega symbol; The watch has been stored and well cared for. Back case is marked 18k 0.750 with the number 42864. If you would like more photos i'm happy to add.
Thank you!

I had my doubt's but wasn't sure. Any identifiers that prove fake? For a fake it's pretty good one, can open the back up now.

yes it's fake but it's a "historic" fake. probably one of the earliest fakes made. at least earliest made in bulk. these were very popular purchases by GIs during the Vietnam war and loads of them are in junk shops near the military bases in the Philippines.

Thank you all, it's really great to have peeps like yourselves to assist the community. I can'y wait to purchase my first Speedmaster!