You might already know this but there is a place that makes custom head badges. I'm betting they could reproduce that badge for you. I realize your original is a decal/sticker, but wouldn't it be cool to have a real metal badge made to match your original?
This is the only link I could find to contact the man > http://motorbicycling.com/showthread.php?t=19584
Maybe it will be something you're interested in.