Comparing a classic car to a new car? Really???
A Factory torsion bar car can handle as well or even better than a new one with proper parts selection. A solid platform with frame connectors, torque boxes, urethane bushings, properly valved shocks and a Borgeson steering box can be quite impressive.
The steering rack is an amazing thing, I will admit that but a $5000 coil over setup is a steep price to pay when you can have equal or better handling at 2/3 the cost by sticking with a stock based setup.
If you are hung up on having the newest shiny object for the car, this logic will not register with you.