This will open a can of worms, but what dimension did you use for the dome fill down?

Did you figure the deck clearance into the equation to get the 9.8cr, or does that 20cc dome volume figure take that into account?

MP used to have a .533 lift hyd cam.....I wouldn't be surprised if that's what you have.

If you're good with a degree wheel you could plot it out and see exactly what it was.