The OEM traction bars are not going to help with body roll. I can however point out one thing I learned - a rear sway bar has less impact on body roll than the front bar. It may be cheaper in the long run to put your one OEM traction bar back on and just get a bigger front sway bar. Unless you decide to completely change out the rear suspension like you were thinking.
There is a really good website I can point you to put together by a guy who has been auto crossing a 1st Gen Camaro for years. He had a lot of good pointers about 1st Gen GM F body suspensions. It's probably a good place to start before spending a lot of money.
2012 Mustang Boss 302 #1918, Competition Orange. FGF replacement 2006 Mustang V6 Pony, Vista Blue. Factory ordered. 2019 BMW X3 (Titled to the wife, but I'm always driving it for her. So I'm claiming it) Old projects, gone but not forgotten: 1967 FB 400, original CA car. After 22 years of work, trashed by the guy who was supposed to paint it. I had to sell it. 1980 Turbo Trans Am 1970 Mustang fastback, 351C 4Bbl, auto 1988 Mustang GT, 5 speed 1983 F-150 4x4, built 302 1994 Chevy K2500 HD 4x4, 454 TBI