I had the same dilemma with my 514 and finally decided to go without a side emblem. That was before paint, so the car looks fine without it. I've seen a source for "custom" emblems here:
http://www.legendarycobra.com/
Click on the 514 emblem in the center of the page and there is information on who to contact. I looked at it, but it wasn't for me, so I chose to go without. I can tell people who ask and those that don't....they don't care.
BTW, while talking about that area of the car, if anyone is interested, I just had my West Coast side louvers fabricated in stainless steel. Didn't like the black look. My source can make more if anyone is interested.
Good luck with the emblem search.
Chuck