A mid 60s Seamaster with a 321 movement. Looks to be in really nice condition for its age. These are very nice watches but not as sought after as a Speedmaster of the same age. I would think that your suggested value is not far off the mark, for an example in this condition. Many will have degraded dials and well worn cases. This one is well above average. However, I would suggest that you raise the same question on the omegaforums.net, where you will get well informed advice.