As
@Archer has said and as you
@jrpippen have commented on, mistakes occur and not everyone at these stations is an Omega vintage specialist with knowledge of all the correct dials for every transitional period.
These service repair centers are well trained and credited people in repairs but vintage pieces are tough. Some pieces were not documented well - even by the original manufacturers themselves. Secondly, no one is perfect and there is a chance the Omega specialist was incorrect in his comment. I have moved hundreds of timepieces, the occasional WELL DONE re dials come through, it's inevitable in large quantities to fall for good examples.
Too many concerns have been brought up.
If you showed me a Rolex retailed by Tiffany & Co and the "O" looks weird in any way, trust me, I would spend many hours to verify before making commitments to purchase or sell. (Especially if I'm spending 10k+) Additionally as a potential seller for this piece you should not pass this as original by the word of one individual. Acquiring Archive documentation from Omega before the sale would be beneficial to you and the buyer. If the dial is original and rare this piece could be worth much much more than current market values. I personally would love for it to be real - it would mean I would have the chance to see this beaut (and possibly bid for buying rights).
You should address that 24, the different boldish font, lack of lume & any patina (if all the lume is gone it means someone either took it off or it faded. Without any patina on the dial I doubt it faded. Look at the dark spots where the lume should be and you'll see a little black dot. It looks to have been taken off.) I'm not a specialist on this period of Seamaster's/Speedmaster's but with concerns like these, take time to look into it and do not dismiss concerns.
When presenting a timepiece for a fair amount of money you should bring evidence to support your claim on its originality. If a few of us had immediate concerns then potential buyers should too, best of luck.
Pinzon