IS your windshield post not large enough to scan with the match camera?
Never an exact match unless you get very lucky. Still going to have to tint and do sprayouts. I've been down this road many times. That's why I call the color library first. I thought every shop owner knew this but I guess not. I've only been doing this for 40 years.
You are correct, however it will get you close if you drop about 20% of the metallic content and color adjust for the metallic drop.
This is how I color match for NCRS.
FWIW Camaro PAINT judging is nothing compared to paint judging in the NCRS.
They will kill you for too high metallic content 30% or more of the paint points GONE...
Also must appear as lacquer, with orange peel.