Let's start this all over again. This time, we're lowering a 1st generation MTH Premier PA-1 with Protosounds 1. I actually started with the non-powered A unit first, and it's going to be really simple.
I started with some research, and from the drawing I found, the height off the rails to the top of the pilot is 4' (1" in O), and 14' to the top of the car body (3.5" in O). This puts the top of the pilot at the right height, but the car body is a little tall in the saddle. In fact, bring the frame down to the top of the pilot will put everything at the right height. It's going to take some machining for this unit, off the top of the truck, and we'll see what we have to for the powered A.