I see what he is saying. In the saddle are the live steam ports from when the engine was a soak. The wishbone branch pipes coming from the dry pipe that carried the live steam down into the steam passages in the saddle were replaced with new branch pipes coming out the side of the smokebox and down into the valve chests. The connection point where the wishbones were connected to the saddle in the bottom of the smoke box had have been blanked off or the live steam would come out when the throttle was opened.
The IRCA engines would have had the same situation.
You are correct about #40 having unbalanced valves. Hooking her up with the throttle wide open was a bit of a challenge. It helped to get into the rhythm of the engine when you did that.