She's a beauty! A drop or two of PolyWatch on the plexi, cotton pad, polish, repeat. If you like, you'll find plenty of tutorial videos on youtube, but it's really easy as pie.
Works fantastic on light scratches. For scratches that are a bit deeper, I suggest looking into Novus. It's also a plastic polish, but the strongest version can take care of deeper scratches faster
Thank you. There is a small crack at the 11 o’clock position near to the dial edge which I’m guessing won’t improve with polishing and I’m loathe to change crystal as it looks like the original with Omega etched symbol
It's not necessarily the original crystal, but it sounds like an authentic Omega crystal. Cracks can compromise water resistance, so keep that in mind.
I've had staining on the dial after an unnoticed crack in the crystal on my Heuer Carrera. (I am amazed it has survived over 50 years with me at all 😁 ) That linen dial is so nice i would value preserving that much more than replacing the crystal, even with a non-engraved one.