rear sway bar recommendations

I traded for a 68 Delta 88 around 1990 & drove it when I met my wife.
Going down the interstate it felt like the front end was moving up & down & in a circle from one side to the other, while driving in a straight line. Went straight OK, just felt funny. Thought front end was worn out, had never felt that before in any car.
Sway bar link on one side was broken, and after fixing it, car drove fine.
Thought 65 Barracuda w/no front bar was going to be like that, but it drove fine without it. 1.03 bars. Never tried pushing in the curves, was just a test drive.