Here's my opinion on that specific rockabilly hairstyle...
It's not something you can rock everyday, without looking out of place. By that, I mean unless you're fully decked out in rockabilly garb, it's not gonna work out for you, all that well. Even in the rockabilly scene, the waterfall hairstyle has pretty much gone extinct, aside from those who are clearly rockabilly eccentrics.
Now, I've seen it rocked well, when it's very short, where it's not going past half of your forehead. It wasn't rocked by a rockabilly cat, and it worked out because it didn't seem over did, it was just how his hair naturally fell forward.
In the Teddy Boy scene however, you'll see it all the time, and it works.
Just my take on this hair situation.