Sorex 28R is about perfect, with Orion JB foam blue(light weight medium thick on medium grip, thick one on high grip track).Never has overheat problem unless you run it in summer. 24R when grip is low, but on high grip track, the car wants to move side to side a bit and traction roll of course. You can do something like shock, springs, droop,etc to reduce traction roll, but the most effective way is to coat the outside side wall(up to the shoulder) with super glue. You may have to recoat it every few runs.
On power steering, try 1.1mm x2holes piston at the rear with 40-45w oil(you can keep the 1.2mm x2holes piston on the front shocks), moves the rear shocks to outside holes on tower, try rayspeed yellow, HPI pink, Tamiya blue or X-ray white at the rear, these are a bit stiffer than Asso silver but softer than Asso blue. These help on-power steering a lot.