I say run PS with small blocks, EFI and STOCK ECUs. Allow traction control. Until it gets ridiculous, allow teams to adjust the ECUs for Fuel/Air and TC settings, etc. Maybe even bring in a rev-limiter, say 10,000 RPM to keep the cost of the internals down.
I think most of you don't understand how traction control works. If it truly slowed cars down, why would race teams use it? What traction control does is manage the efficiency of the power being put to the track via controlling wheelspin. In simple terms, instead of letting a car spin the tires, it slows either wheelspeed down via application of the brakes or engine speed down via rev limitations or both to keep the car moving forward and building the all important mechanical vector known as momentum. Basically, a car that shakes the tires and pedals (loss of momentum) is not going to beat a car whose ECU manages the shake part of the track and keeps the car moving forward (minimal or no loss of momentum).
In a street car, TC is activated to allow you to keep control of a vehicle and prevent a crash. When your PT cruiser activates TC, your wheels are still driving rather than spinning and it should give a greater degree of control in an emergency situation. TC in a street car definitely slows a vehicle down, but that is to prevent soccer moms from cracking up the family car, rather than negotiate a race course efficiently as possible.
