mags,
You need to get someone to cut it down and rethread it for you. I've done a few, but really don't make a business of it. I'm getting ready to do one for a friend. If you want one, let me know. for $25 I'll get you one, cut it down and ship it to you via 1st class mail. Modding the reflector will be up to you, but for and extra $5, I throw in an IMS SO17XA reflector for it.
If you want me to do it, PM me with a 1st and second choice of colors. I'll probably be getting it a Walmart.