ProComp/Speedmaster aluminum heads

That’s why I suggested option “c” ;)

There are some typos/erroneous info referring to the “spring rate” in that “Valve spring tech” article.

To illustrate this point consider two springs that have approximately the same seat pressure at 1.800-inches installed height; one at 123 pounds-per-inch and the other 124 pounds-per-inch. The spring with 123 pounds-per-inch seat pressure has a rate of 408 while the spring with 124-pounds-per-inch has a rate of 251.

Click to expand...

The installed height load is not rated at “pounds per inch”....... it’s just “pounds”.
If you don’t really understand spring specs, that could be confusing to someone.
The “spring rate” is determined by the change in load over a specified distance.

I see those types of misprints in magazine tech articles all the time.