Zenith Pilots are massive so you've not got much chance of hiding it
It depends if you like patina or not. Personally, I'd buy an old watch like that for the patina. If you were going to overhaul the movement, refinish the case then it will look pretty sharp. For an older watch such as the ones you're looking at, you need to find a trusted watchmaker to do the work. Cost is entirely dependant on what needs doing.I am researching buying an old Omega Seamaster (60's/70's) It looks like they often go for under £200, but often have a fair amount of "patina" at this age. How good would a watch like this look after a full service, and what should I pay to have it done?
Oops, Dial... My bad
The Ceramic will add to the price as will the slightly more advanced movement which has 56 hours power reserve vs the 48 odd of the other two.
Whether that along with the extra styling equates to £600 worth of extras though is for only you to decide.