Maybe the best way to have told the improvements from any one improvements made to the car would be better judged on the same track and seeing how the times improve.

Like you said your car must have been fairly tight in the seat of the pants feel so any small improvements will only show up in small increments measured in small time increments in the track times.

My friend has a stock 68 Charger R/T and it soaks up the road bumps etc like you mention your Charger did does as well. I was very impressed how much better his car rode. Back then all of my junk had Super stock springs on the back and I was driving it on the street......Im on board with the XHD leafs now.

My 72 is basically an E body in alot of regards it might show different results from the frame connectors also. Since the B body cars always sounded better closing the doors over the E body cars so Im hoping for some improvements in that area as well.