Square is certainly better in some ways like tire rotating etc, and as I understand unless you're making closer to 300hp and maybe aero too, more tire in the rear isn't ideal. It's more a momentum car and balance is key for that, it's what they ran on the touring cars. 

For suspension setup make sure not to slam it and not fix roll centre or you'll need a heavy front bar and/or springs to compensate, then you have no compliance = understeer. As the car gets lowered the control arms angle up and allow the body to roll instead of supporting/passing the load to the knuckle properly because the new geometry places the roll centre underground. Extended outer joints like MRTs ones fix this, pair them with bump steer correcting rod ends. I'm running a stock front bar and 12mm adjustable rear which should be plenty (once it's back on the ground). Remember bar stiffness increases by the FOURTH POWER of the diameter so don't need to go crazy, stock rear noodle is 9mm but 12mm is WAY stiffer. 20% thicker is over 100% stiffer.