I don't have any suggestions directly, but did you try calling a consignment shop or high-end tailor and asking them if they can recommend someone?

I have a great dress of my mother's which was purchased in the '60s. Hand made with lots of beading. It fits me like a glove, but I need to get it cleaned. I've tried several dry cleaners and none would even attempt to clean the piece. Does anyone have any ideas on where to go?