Just got my first Vintage Watch- Omega Seamaster De Ville - need help!

Hello all,
This is my first post- and I imagine a lot of people start on the forum like this. I am an avid watch collector (VC, Rolex, Omega, Zenith TAG) but total noob to vintage watches. My first nice watch was an Omega, so I thought why not for a vintage piece as well! I won't bore you with all the details- but I bought the watch from someone who was very upfront they had no knowledge about it at all (came in a box of watches at estate sale). So we met at a local watch repair shop who opened it for me. They thought it was in great condition, considering the age. It ofcourse needs a full service and the rotor axle replaced (as is common on these movements, I guess). However, I am having a hard time dating the watch or learning anything about it. I threw the movement serial number into this online look-up tool that said it is from 1971. However I keep reading the Seamaster /De Ville was only made in the 60's?

Anyways here are the details (and included pics).
Seamaster De Ville with Date
Black Dial
Gold case (I assume) Can someone tell me is it a solid gold case?
Movement serial # 33601875 a 563 movement
Case back stamped KM6292, LL6287-1 and large 881028
Besides service, needs new strap and missing the Omega buckle

I left the watch to be serviced, so these numbers are from pics I took. I think I am readng them correctly, though. My final question- did I do okay on the price? I paid $300 for the watch and the full service labor + parts & tax for $495. Thank you for any info you can share! Not only for this specific watch but any other cool need to knows or fun facts, would also be appreciated.

P.S. Any chance or leads on where I might find a period correct Omega buckle?

This might be helpful?

https://www.omegawatches.com/en-us/watch-omega-us-collection-seamaster-de-ville-km-6292

A gold case would have the same case stamps like all the other brands , you collect. Is there a Swiss made under 6 o' clock ?

Judging by this thread, it appears that a 1971 Seamaster De Ville with a 563 movement is a legitimate possibility.

From the lack of a hallmark on the case back and the info on the database, it's clear that the case is not solid gold, which would have made it one hell of a bargain for $300. I still think it's a very good buy if the dial is original. It looks ok to me at a cursory glance, though the apparent loack of a Swiss Made at the foot is cause for concern. However that was a very expensive service, if the $495 is for that and not the all-in price of the watch.

It's hard to see from that one picture but the crown might not be the original one.

Good luck with the Omega buckle. There are loads of copies about and it's an absolute minefield.

It is not a gold case, the hallmark is missing from the back, but that is totally fine. The black dial is looks gorgeous, and it is a very cool vinatge piece. Congratulations

Note that not every case appears in the database, so don't base that decision on what you see. It can lend support, but it doesn't override what you have in your hand.