Although a totally different issue to 'will I fit' I'm not convinced that anyone regardless of height is 'safe' in a roll over situation in a soft top car. Sure in an ideal situation where the car is placed upside down there should be room between the top of the screen, roll bar and head, however reality is that the screen flexes somewhat, the roll hoop has an inch of plastic on it, both almost certainly dig into the ground and use the head and a plough and a standard seatbelt even with tensioners will stop forward movement but certainly allow vertical 'drop'
All in all I think we need to keep Z's the right way up.
In competitive off roading where I'm often upside down (usually accidentally) I'm secured by a severly ratcheted down 5 point harness, competition seats, a full internal roll cage with seats integral to it and a full external cage caged linked to the chassis and many other points. I still get battered.....