Rather than someone who specializes in wedding dresses, I think you may have more luck with someone who does vintage restorations for museums and such.
I don't know if you have a place local to you, but I did find one place on the net that may be able to help you.
IFI Services.
At the very least you can shoot them an e-mail and see if they can help you out.
Good Luck!
~spidey