Cut the shell off that one and measure the fuel ring. If it’s over .100 wide the A/F meter is correct and it’s rich. That ring should be .060-.080 wide and no more than .100 wide.
How pig rich do you think it would be if you turned the plug brown???
Edit: I keep forgetting to ask if your distributor is locked out. If it’s not it must have a very short, fast curve.