Justin Rose, whom I've been working with since 2009, is 6-foot-3, but he swings as if he's only 6 feet tall. The feeling he has is that there's a ceiling just above him, and he'll bang into it if he pulls up—which might be the worst swing error you can make. Staying in posture, as I'm demonstrating here, does two things:
It promotes solid contact because the club swings on the same plane back and through. You don't have to make any midswing adjustments to get the club back to the ball.
It allows you to push down with your legs, and more ground force means more power. So take the club back slowly, maintaining your address height. Then rotate toward the target at that height. You'll pivot around your spine and hit the ball powerfully.