Help me buy my first Omega watch :)

Rochete

Bad redial. Crown looks dubious, perhaps that's why it isn't properly shown. Laughably overpriced, if you're even considering paying that much for such a piece of crap I suggest you to have a look at the Private Sales subforum here, plenty of honest pieces on sale.

Jokr

Looking at the watch the font seems to be off. you might want to avoid it

Edward53

Welcome from a fellow Brit who also likes the Seamasters of this era. Unfortunately this one, as has been pointed out above, is a bit of a shocker with that bad redial and replaced crown. There's no side on shot of the crown so I can't even tell if it's actually an Omega service crown, but it certainly did not start life together with that watch.

I don't know that seller so can't comment on their knowledge or integrity, but here are a couple of observations:
That person has numerous watches for sale so they should know their stuff. I've just looked at several of them and they are all redials in the exact same wrong font. What does that tell you?
Read descriptions very carefully. If they don't explicitly state that a dial is original and unrefinished, be doubly alert.
The same applies when a picture of something important is absent, in this case the logo on the crown. But as mentioned, this is not the crown you'd want anyway even if it is genuine Omega, as it's the wrong style.
It is dangerous to assume a seller is "trustworthy" from their feedback. Input from experienced collectors with no axe to grind is a much better guide.
There aren't many vintage bargains to be had from business sellers, most of whom I'd give a wide berth to.