Except the measurement of the engine's height seems to be taken a bit too far forward. The man oiling the rods/bearings appears to be well in front of the tower legs, and the yellow lines are measuring well in front of him. So if that's the "X" you're using, you're under-estimating the size of the tower. You want to (as close as possible) measure the engine where it lines up with the front plane of the tower, since the 3/4 angle means the scale of the engine changes with distance.