Yeah you can handle the design well, but apart from the cool head piece addition, it doesn't seem enough of a deviation from regular seviper to warrant being a mega-evo (or regular evo for that matter). I rkn play a bit more with it and try advancing seviper's nature/character to get more out of what an evo (or mega) needs.
The dude below had a good idea about curling it up. Maybe something else happens. Coiling alone wouldn't suffice imo.