I think with that level of (possibly unsurvivable ) vertical deceleration there is every chance the overhead panel would detach, it is fairly easy to do so for maintenance purposes. In spite of not being so tall I have taken chunks out of my head more times than I can justify just taking my seat. If you compare the cockpit environment with say a modern car it is very unfriendly to a human body in a crash situation. Full of sharp preturbances, and , as I found out to my cost once in a car accident when I head-butted the windscreen, given serious deceleration , seat belts do stretch. Ask Mika Hakkinen.