it's not so much weakness in the strut towers that'll let them flex its the chassis ... or lack of in the case of a datsun ... that allows the motor to twist the body so much ...
all big hp cars will suffer from chassis twist under a big launch/acceleration, watch with drag cars, generally one wheel will lift alot higher that the other depending on chassis strength, the addition of a tower brace may help in the situation but they were originally designed as a suspension component not a body strengthener