In addition to the Spring rate charts, remember to take into consideration the Shock oil and piston bore # when choosing Springs.
This adds more into the equation.
You can effectively tune the spring rate inbetween the Spring rates on the chart using a thicker or thinner oil.
Thicker moves slower like honey, best for smooth high traction tracks.
Thin moves faster like olive oil, best for bumpy tracks.
Think of how fast a truck tire needs to travel over large bumps compared to a race car on a smooth surface. Trucks benefit from a wide bore and thinner oils than cars.
Our car's tire is not traveling very much so therefore benefit from a stiffer rate and thicker oil.
The shock piston has a bore for the oil to pass through, smaller bores yield slower rates and stiffer shocks. Large bores don't allow the oil to flow through almost freely.
Thicker oils won't heat up quickly and thin out or gain air bubbles and foam as much as thinner oils do.
Adjusting rebound by adding more oil is another adjustment.
If you disconnect the shock from the chassis and compress it and it will not expand (or really slow) it's dead, just like on your people car.
Empty and refill it and check it again after a few runs.
On top of it all, a setup that works for one driver may not work for another based upon driver habits. Tight turns, wide turns, etc.
Hope this helps.