Omega Semaster 2518 advice

Hi,

I need advice and valuation on this (looking to buy this one...).
Does everything look legit? Seller claims dial is untouched.
14k Seamaster OJ 2518 with 343 movement. Says here that only 5000 pieces were ever made (first year of seamaster watches?).
http://www.omegawatches.cn/planet-omega/heritage/vintage-details/15747/
Almost identical to this (this one is 18k with slightly different dial?):
http://www.omegawatches.com/planet-omega/heritage/vintage-details/14715/
What do you think? Any advice and suggestions are welcome!