I don't have a picture of the routing of an original cable, but I'm pretty sure the cable housing leaves the "P" clamp at the control lever bracket under the hood, travels forward over the hoodstand and loops down and back around 270 degrees and fastens to the bracket behind the throttle disc with another "P" clamp. (the cable would be coming straight up from down near the tractor frame.)
I'm thinking there's a hole in the lower right corner of the hoodstand for the housing to pass back through, but my 400 is buried right now so I can't look.
Figure 6-42 shows the correct attachment of the inner cable to the throttle disc, but it would be turned 90 degrees ccw for your WH application.