Rather than spending time on the board detail, it would give you a bigger return in accuracy to correct the layout of the underbody brake components, which is a mirror image of what it should be. For casual layout viewing, the most easily seen details are the brake valve, cylinder, and air reservoir. Adding the rods which connect the various components will make the car appear even more detailed, although the slack adjuster can be a bit of a pain. As far as brake piping goes, add it if you wish, but on the layout it is almost unnoticeable. Anyone wishing to learn more about underbody detailing should check out Ted Culotta's articles in the August and September 2003 issues of Railroad Model Craftsman, where you'll find not only information on both AB and K brakes, but also some superb modelling.
Wayne