Color has nothing to with the size hump on the head.Check out cichlidconnection.com and talk to Gage.They have the pie-balled Labiatus that you are looking for.
If looking for a large nauchal hump you want to look at red/white Citrinelus (Midas) not a Labiatus (Red Devil). Most if not all of the fish you'll find at the chain pet stores will be a cross of the two while some are beutiful fish they don't all develope the NH your looking for. Find a reputable source, you could browse through the vendor section and look at what's available. If you really like the red/white color a with a big NH look at getting an Amphilophus Xilo. very nice looking and grow about ~10" on average.
You can call all the Petsmart stores in your area and ask them. That's what I did when I wanted to find one, and several stores in Atlanta had them in stock. Petsmart isn't the best store in the world, but they do carry really nice Midas/RD.