Reply to "Basic adjustable shock help"

I agree with Mike. Stock springs were 300 front and 350 rear. A few of the race-oriented vendors in the U.S. sell very stiff springs along with their adjustable shocks. Others, more aligned with street performance, sell springs closer to stock but of higher quality. Your stock springs have likely deteriorated since 1972... Unless you're actively racing, or drive only on very smooth streets, such high spring strength will result in a noisier, more uncomfortable ride and likely, a deterioration in handling. Tires get no traction unless they're in contact with the road, and over-stiff springs will cause tire bouncing unless the damping is set very stiff as well.