Geoduck in Portland
I would call Hiroshi ((503)619-0580), Murata ((503) 227-0080), Ocean City ((503) 771-2299), and Wong's King (contact by website: http://www.wongsking.com/contactus.htm#).
Japanese and Chinese are your best bets. Understand that the stuff is not cheap and can lead to an expensive meal if you are paying 'market price' instead of set price/by the plate. Chinese style can often be sold "market price" so ask what that means before you order so there are no surprises later. ;o)
And understand when you call that there might be a language barrier unless you can communicate in Japanese and/or Chinese.
38776 Proctor Blvd, Sandy, OR 97055
Ocean City Restaurant
3016 SE 82nd Ave, Portland, OR 97266