Based on what ive seen i dont think its an outright no no from the CAA. I work with 2 pilots on a daily basis who are at least 6ft5 minimum. They might be taller. all i know is im a tall guy, there quite a way taller than i am.
As for the measurment requirements for support and comfort in the flight deck, im not sure if they have had to have gone and got that checked specificaly but at that height they are both employed by major carriers.