Do I need bigger torsion bars?

My two cents:

In both my 66' Barracuda with the slant6 and the 72 Dodge Demon 340 4 speed (approx. same weight as the 318 you have) I installed the Mopar Super stock springs AND the 383 torsion bars for drivability and control. I love the feel of hitting a corner and bumps and the car almost never bottoms out. Let's face it, roll control starts with a suspension that cant handle its own weight. Do they ride rougher or stiffer? No they feel right. Before with the orginal bars they were over 40 years old and rode (please pardon the term) "loose" and lack luster. I realize that it is a few hundred bucks for front and then the same for rears but when you can afford it, a suspension upgrade is a good thing. Sway bars on an old set of springs is nice but is working way harder to maintain control when the springs cant handle the load.

Also the car looks great from the photo! Best of luck with your quest for a great car!
Joe