Clarke (Sweetone & Original), Shaw, Copeland, Hudson Winds… Any others?
I think the Sweetheart pro is conical but you might want to e-mail them about the details!
http://www.sweetheartflute.com/whistles.html
Also, Mack Hoover use to make some conical whistles from the tip of a ski pole!
Nate
Jonathan Swayne’s wooden whistles are conoid bore, though that is not necessarily apparent from the contoured external profile.
Bleazey whistles are conical, and one of the two Susato lines is slightly conical, too.