Went back and remeasured the power chassis model and had a few dimensions that were off in the computer model. Off enough to mess up the sizing and proportions of the overall model. Turns out I need to make the Viewliner model smaller than what I had originally, keeping the truck centers on the Viewliner and the Bachmann motor block the same distance.  Unfortunately that caused a couple problems when I scaled down the Viewliner model.

Here you can see the Viewliner model over the red stand-in for the motor chassis. The red motor frame is busting through the model shell in some very inconvenient points. I already knew I had to modify the fuel tank weight on the frame, but the circuit board on top punching through the roof doesn't look very nice. Not only that, the shell would be extremely thin because it's so close.

Although the model would be the right scale in proportion to the 9mm track, it isn't very practical, so I had to pinch myself and fudge the accuracy enough to make the model work.

I started by stretching the model vertically slightly, then enlarging the overall scale, and finally lifting the shell so it will actually ride a little bit higher. The goal is to get the circuit board on top of the motor to sit underneath the interior roof of the shell (colored in blue). The shell was also pushed backwards so the circuit board corners where moved into the higher part of the sloped roof.

The overall enlargement was about 10% larger than what is proportional to the track. Not too bad. What I did lose in accuracy the most is the wheel placement. I'm hoping I can hide the spacing difference with the truck cover plates, keeping their proper placement-- even though the wheels are not where they should be. The front truck pivots are lined up, but the back truck did not fair so well.  Luckily the wheels will be painted black and in this scale-- with the model at only 2.85" long at this point--shouldn't be too noticeable that the wheels are in the wrong spots.

Here's a 3/4 view of it ghosted...

Designing this model has been like designing a Hot Wheel or Matchbox car; since the scale is so small, you have to beef up areas that wouldn't survive the manufacturing process. The window frames and side mirrors are good examples of that. Quite a challenge but kinda fun!

Also, the headlight and Mars light is in! Non-functional at this scale!