Yes, there is a general rule that correlates shock oil to spring rate. Actually it's the damping ratio, which depends on the Damping Coefficient, spring rate, and mass of the components supported. You may find that your best matches will converge on a consistent damping ratio number.

Here is the wikipedia explanation for Damping Ratio: https://en.wikipedia.org/wiki/Damping_ratio
The main thing to take away is that there is something called Critical Damping, which is the amount of damping needed to most quickly get back to not moving without overshooting (bouncing). Think of it as a "plop" without the car rising back up. The fastest time you can have that happen without bounce back is critical damping. If it comes back up, you have "underdamping", if it slowly settles down even farther (but doesn't rise back up), it's called over damped.

If you notice, Damping Ratio, is simply that... the ratio of your actual damping coefficient to the Critical Damping. Critical Damping is a purely physics based value that you can calculate yourself if you know your mass and spring rate. c_{c}=2*sqrt(k*m). You can change the critical damping by either changing your spring, or changing the mass. Your Damping Coefficient is purely based on what you do to your shocks, which includes your oil and your piston choice. So, if your mass stays the same, and you can change your spring rate, you will change the critical damping. If you don't also change your damping coefficient (oil and piston), your damping RATIO will therefore change.

It turns out, theoretically and supported by race car drivers, the "ideal" damping ratio is about 0.67. This value, theoretically, is underdamped and allows your suspension to get back to steady state as quickly as possible (even faster than critically damped, even though it has overshoot). This allows your suspension to be active but not overactive.

Now, while I said 0.67, this is not a hard and fast rule. Some forms of driving/racing will find a lower or higher value is more ideal. For instance, your average passenger car is made to be around 0.25 or so. This provides a comfortable ride. I've read where F1 race cars are over damped to around 2.0, but they have very advanced and special reasons for doing so. Autocross finds 0.65-0.70 tends to be the best overall. I have calculated damping ratios on our off road cars, and they tend to be around 1.0-1.1 for a box stock setup. I've hypothesized that the reason for this is the jumps, and is the compromise you must make because it's such an important part of the race.

So, to make it more complex, there are different damping ratios you can calculate. The DR you are seeing on your bench is the typical one where you are controlling the motion of your tire/wheel/suspension. This is the main one in which the numbers above support. Then, you have another damping ratio, where your Mass is your sprung mass, or the chassis of the car. In this case, you assume your wheels are locked to the ground, and you are controlling your body motion on a landing of a jump. If you notice, your chassis (divided by 4 for distribution on each shock on your car) is much heavier than your tire/suspension. So, your damping ratio will be different in that motion.

Thus, I propose a different way to approach shock setup and use what I call a "pack ratio". Pack ratio is simply the ratio of your damping coefficient under impact, vs your damping coefficient under normal slow speed operation. Then, if you can control that ratio (think VRP game changer pistons), you can independently control the damping ratio for driving (normal damping range controlling wheel motion while driving), and impact damping when you land jumps.

RC Crew Chief does have the suspension modeling, and now one of the setup numbers it provides is now the Damping Ratio. In this program, you enter all of your dimensions, mass, springs, oils, etc, and in the end, it will calculate Damping Ratio for you. If you enter your car into that, and try out different springs/damping, you should start to see a good correlation between the number shown, and what you see on your dyno.