Some people paint the springs. With the OC/Gator/Viper being the second best selling platform, there are many builders doing their own thing for product recognition.
The gold .085" wire springs are the only ones I have made a chart for, as there are very few people using them. I can email that to anyone who needs it.
The standard .090" wire spring as supplied is a raw steel/silver in appearance. It is noticeably longer than a Bully spring, which is one of the main keys to the clutch working properly.
When Tim Baker first designed the clutch, we used the Yellow spring from the Horstman enduro axle clutch as this removed any sensitivity to air gap from the clutch. A Viper style clutch will still work even if the air gap is as tight as .020" or as loose as .060"
A good starting point for 3800 rpm on a stock clone is .430" using a Bully brand spring height gauge.
The spring is fairly linear so a .020" change in height is "about" 200 rpm. Above .450" it is less than 200, and below .380" it is slightly more than 200rpm.
Depending on lever style, as there are about 12 different lever style available, that is a good guideline to follow.
Shannon Halbert and James Raines use a different style retainer than I am familiar with, so if they built your clutch, you may need to contact them to get a good ballpark height to start with.
The main thing to keep in mind, is make sure springs are from same batch (or matched) and that you are consistant in your settings. Buy a Bully brand spring height gauge, and check it often with the supplied calibration ring.