I'm Asian, Chinese to be exact. Generally in our group of friends, customers, and family, your RIR or red colored bird is just fine for meals and often females are preferred. For stews and old hen is preferred as it has more flavor. Really, in the end, the color doesn't matter as long as the bird is alive and running around. For the American born families, the Cornish x meat bird like the ones from the store are preferred to make dishes that don't involve the whole bird.
Black skin chickens, like silkies, are used for medicinal soups, and are not really a "meal" so to say. The meat is just there to flavor the soup.
You may want to figure out if they want the birds alive or if they want them prepared. If prepared, figure out how and what they want to keep. Often, I need to keep the head and feet on, keeping the heart, gizzard, liver and ovaries if it is female. Presentation can be important and so often it is easier to sell just a live bird.
That said, demographics differ and it would be easiest to just ask them what they want and if you can't do it, just say no. Asians haggle on prices of live goods so stick to your minimums if you choose to do so.