Trim Tag Special Paint Decode

[travlnz28]

This trim tag paint number on my 70 LS5 supports the handwritten note at the bottom of the build sheet and the inside of the door clearly shows the original color. My questions are:

Could GM have used a paint code from Ford or Chrysler? The color looks like Grabber Blue or the Richard Petty Blue and I don't remember a GM color like this.

Did Benjamin Moore mix paints for the auto industry and is that what the BM in the paint code relates to?