The probable reason you have such difficulty finding the proper color is that there is no "right" answer. In his book on Japanese Aircraft Interiors Robert Mikesh basically says if it looks right, it is right. What I do is to first paint the area an aluminum color using Alclad II. Then I mix Tamiya clear green and clear blue until I get what looks right to me. Next I thin it and spray in on light coats to build up the color. The Alclad shows through and I have the interior I want.
Now the exterior is another story. I was just the USAFM and tried to photograph their A6M2. In Pearl Harbor colors it is some shade of a tan or maybe an amber color. It's not the light grey we see in so many instruction sheets.
Duane