Anyways, I've known taller and bigger guys who are Chally 2 crewman (not so comfortable as a gunner) but managed okay. The Gunner's seat is uncomfortable for alles, and I'm a short ass! Driver's seat is sleep city even for big guys.
Some of the sweats when I first joined up used to say the inside of a Chieftain turret was pretty roomy to start off. Not exactly dome of St Paul's roomy, but a bit of space. Then we started bolting all the new fire control system bits and other gubbins in & it left us hunched over.
A Troop Leader in my first Regiment was absolutely huge. The problem here seemed to be with the trunnion tilt compensators, because he was no stranger to a fish supper.
One of the Troopers was very tall (rumour had it 6'9" or so) & built like the gable end of a crisp. He could drive Chieftain OK, but had a bit of bother with a closed down 432. Think he ended up in MT where there were vehicles with a bit of headroom.