Quaggas actually have, contrary to the current Rau zebras, usually quite broad stripes with less space between them as far as I can see. I assume that most skins, like that one, are bleached and do not represent the original colour of the fur. For that, I used contemporaneous paintings such as the one below as a model.
|Painting based on a living Quagga by Nicolas Marechal from 1793|
One noticeable difference between Quaggas and Rau zebras might be that the latter have broad stripes that fuse with the brown background while the Rau zebras tend to have continuously finer stripes that disappear towards the end of the trunk. But this is just my personal impression and we don 't know what future Rau zebras will look like yet.