Claudius, Look at more than the pressures... The installed heights and spring rates and especially the coil bind figure are what you need to compare apples to apples and these vary from part number to part number and manufacturer to manufacturer. It's easier for me to just use what the cam guy wants... and in some cases, a spring may look like it will work but due to something else (like safe harmonic range, rocker ratio or overall valvetrain weight, too large a diameter of wire in s single spring, etc) the other spring may not work as well, over the full rpm range, or for as long. So the right (or usable) spring has nothing to do with compression, type of head, or block. So for the two cams listed I'd go something like Comp 901-16 would work for the Lunati 401 , but the 402 IMO needs more and that one the 942-16s. Unless your goign to buy new retainers to raise the installed height I dont think the 972s are the best way to go. They have a coil bind height of 1.195. If they are isntalled at the std 1.650 height with a std retainer, the spring will bind at .455 at the valve.