I don't think I have ever seen a Seamaster-less Seamaster of this age before.
$600 is too much, considering the dial damage between 2 and 3 and the questionmarks re. the Seamaster script.
@seekingseaquest I was thinking the same about the early bumper Seamasters (the very first ones), but then I reminded my self of this video:
Here is a comparison done by Omega Enthusiast of two examples with 15.xxx.xxx and 16.xxx.xxx serial numbers and caliber 267. They are almost identical, but one has Seamaster on the dial, the other does not.