I would personally rank overall condition as much more important than whether or not it is chronometer rated.
Take a look at
@padders case geometry; that’s what these models should look like. Gold marks more easily than steel so the chances that a solid gold, filled or capped model has been polished and lost that original geometry are pretty high. If you are set on gold be very choosy, don’t just buy the first crap that crosses your path.
If you go for stainless steel look at the condition of the mid-case primarily, and the lugs in particular, these are no longer available but most other parts are still stocked by Omega (bezels etc).
If you see two reference numbers in the caseback it is probably a service replacement, this isn’t a deal breaker but you can cross check that with any statements about “all original”. Try to find one with a single reference number correct for the model you are buying.
Lastly, look at the for sale section here on OmegaForums, everything and everyone gets well scrutinized so a much safer bet than eBay or Chrono24.