I once got a stock 1967 Mustang up to 110 on a country road... that’s when it started “floating”... stock suspension was NOT made for those aerodynamics!
Yup, unsafe without modifications. Stiffer shorter front coils and shocks in front, lowered frame, and an air dam in front will help stabilize it. That's what I did to a few of my cars, without it the floating is scary as hell.