My first thought was "That's a good use of the head."
Then I started to think it looked a bit big on it. What would be really cool is if you could dremel out the inside of the Neo Viper head and make it a helmet, then find a small head to fit inside it.
Your use of the weapons on that back pack are down right brilliant. I really like the shot guns.
Go to Cobrastickers.com and get yourself some silver Cobra logos and that guy would be perfect.
Good job!