Torsion bars are at the pivot, where coil overs aren't...
so the torsion bar spring rate ratio is 1:1,
Where you have to take the distance from the center line of the spring to the pivot divided by the distance from the pivot to the lower ball joint to get the "at wheel" ratio compared to the spring ratio...
Since it is not a 1:1 ratio, the spring rate is much higher for coil overs, than torsion bars to get the same "at wheel" ratio...