on any bike if the airscrews are in the airbox side of the carbs they meter air. So in = rich out= leaN
If the airscrews are on the head side of the carbs they meter fuel. so the opposite applies.
He has a 350, so his are on the airbox side.
To complicate things even further, though, SOME of the screws that are on the head side of the later carbs aren't mixture scres at all. They allow either more or less of BOTH air and fuel. Hate those.