There are several wheel shops that can probably do that, providing there is enough area outside of the dropped center to cut and weld. I would think that you might be better off getting a new rim outer and having your center welded in.
I don't know what kind of rim you are using, but you may find that the style you want in the width you want are available from wheel vintiques or stockton wheel as well.
Stockton wheel is somewhat local to me, there are probably shops closer to you that will perform the service as well...
http://www.stocktonwheel.com/contacts.htm
Do a search here on the site for "narrowing rims" and you will find some more threads on this subject.
Later, mikey