If you install the coupling rods on both sides rotated by 90 degrees, you do not need to synchronize the wheels with gears. This is how the tie-rod drive is solved on real locomotives as well.
Hi!
It turned out great!
I missed the slanted engine roofs a bit, but looking at pictures of the original locomotive, with this paint job the slant isn't as noticeable and your build reflects the model quite well.