Where are these RMS/Noise Floor numbers located?

My method - based on your extraordinary help:

You’re welcome, but that’s not my extraordinary help. That’s the other process somebody else published. My mastering publication started with a rumble filter and uses special RMS Normalize.

Use either one—whichever one works for you. Fair warning that ACX wants all the chapters to match, so there is no swapping processes in the middle of the book.