You don't state whether or not you're looking for a pie-pan dial, that will have a big effect on the price because the pie-pans are more sought after.
Both case references refer to the dog-legged variants which were sold with and without pie-pan dials, the pie-pan dial was also used on other case references between ca 1959 and 1970.
I own a couple of pie-pans but neither are the dog-legged variants, I`ve also worked on a few over the years. If I was looking to buy my preference would be for either an original dial and handset in excellent condition or a watch that's had a service replacement genuine Omega dial and handset. Scruffy duials and hands might give the originality purists a warm feeling but they do nothing for the aesthetics of the watch! Like all things Omega the correct hands and replacement dials were available until 2014 but now can`t be sourced readily, not sure what the Omega accredited repairers can source thesedays but it might be worth finding out. If the dial and hands aren`t right the watch will never look right, there are some good refinished dials around but to a keen eye they will always look wrong, that's not to say the watch won't look appealing but it will always get the purists scratching their beards.
Polished cases has become a contentious issue, I prefer the term 'refinished' because it's far more accurate. If it's done carefully the results can be excellent, any loss of sharpness is minimal and worth accepting to have a watch looking as it was intended as opposed to being a scratched up mess. Again, the purists will be scratching their beards over this, but the cult of 'originality' can be taken too far and consequently loses context, a scratched up battered watch might be deemed original because it's had no work done but it sure as hell didn`t look like that when it was originally sold as a new watch!
Constellations have become collectable over the years and the originality cult has a big effect on values, much as I decry it I will caution against paying very strong money for a watch that doesn`t tick the right boxes in terms of correctness. A watch that's lost all definition to the case through over-enthusiastic refinishing shouldn't command top money, neither should a refinished dial with a generic handset.
Best way to buy is to look at watches for sale on the internet (Chrono 24 etc) and try to develop an eye for what's right and what isn`t. However, there's no substitute for handling the watches and literally getting a feel for them, eventually you can almost sense what's good and what isn`t.
Least of your worries is the movement, they're fairly robust and the problem areas can all be addressed, but parts are getting expensive and harder to find. I have a good stock of the bits that usually need replacing but once they're gone they're gone, I`ve stopped trying to buy replacement stocks because the prices are getting silly. Easiest problem to detect is a worn rotor bush, if the rotor is rattling against the caseback and movement that's a bad sign. However, at the risk of upsetting the Vintage Omega Beardscratchers further, witness marks on the caseback and movement caused by a worn rotor bush shouldn't be too off-putting, the rotor bush may have been replaced is now fine! Of more concern is whether the movement is a genuine 561, 564, or 551, these are the chronometer versions and depending on age or date/non-date that's what should be present. The stampings are on the train wheel and auto-bridges, which can easily get swapped. Generally, the colour of the plating on these bridges should match the mainplate if all's original and correct, but the rotor itself may have been swapped. In the past Omega supplied replacement rotors with the bush and rotor axle all matched up and this was how a worn bush would be addressed, don't be surprised if the finsh on the rotor doesn`t match the rest of the movement.
Original crowns are another contentious issue. According to the purists the correct crown should be 10-sided, but I`ve seen contemporary adverts where a conventional crown was present and that's good enough for me. Suffice to say that the original crown has probably been replaced over the years to maintain water resistance, I place a higher priority on this than having a precious 10-sided crown that pisses water into the watch when it gets splashed......the beardys will disagree. Sometimes I can restore a crown by fitting a replacement O ring, I always try, but it's 50-50 whether it'll work. I`ve seen good quality fake 10-sided crowns for sale in the past too, which muddies the waters further.
Despite owning a largish collection and having plenty of experience fixing these watches there's a reason I don`t frequent the Omega forums........I'd upset the beardys and I wouldn't last long!