I am thinking you just fill the transmission to the rear check plug. You can fill through the pipe plug near the gear shift lever.
After you run it a few minutes it will fill to the front check plug at the Amplitorque of its' own accord. It funnels oil thrown from the gears up through the case to get there.
On my Jetstar, there is a street elbow on the front of the housing and it turns up and has a pipe plug in it. The level in the 3 point is about perfect if it is brim full there. (Not all jetstars have that elbow on the 3 point and my 445 has none either.)