Hi,
would say the rarest is the white face with the roman dial, which is not so impressive if you see it on pics but is really amazing if you hold it in your hand, just one of the most unusual dials heuer ever made and believe one of the top low volume models of heuer, only saw one white in my life so far which is on the dash chrono section.
Came across possible 10 black ones the last 4 years, for me personally cortinas are best new old stock as there are quite tricky surfaces/corners/sides...Is there any chance to get real production numbers ?Best AMH