Reading your OP and looking over your initial set-up there is really no reason to rush to put a rear bar on this car. Your overall combination, i.e., tires combo, Comp Eng shocks, lack of tubualr uppers??, etc. etc. will hold you back from doing anything requiring the fine tuning of a rear bar.

Work on the front of the car first, and when you decide to take the next step with shocks/ tires and correct rear springs then I would think you consider a rear bar.

We run a rear bar on a Big block car, but we also run 26 way adjustable shocks, 1.12 front bars, 1 3/8 Hotchkis sway bar. This combination still has a moderate amount of oversteer, but I like it.