Had a friend convert the soft domes in his Dunlavy's. He found some that were a direct fit but required lots of playing with caps and resistors to pad them in. Fried one or two in the process. Even replaced the ribbon elements with aluminum foil.
http://www.kellsieavdesign.com/ribbon.htm
http://www.lautsprechershop.de/hifi/index_en.htm?/hifi/baendchen_en.htm
http://www.aurumcantus.com/g2g3/g.htm
http://www.kellsieavdesign.com/ribbon.htm
http://www.lautsprechershop.de/hifi/index_en.htm?/hifi/baendchen_en.htm
http://www.aurumcantus.com/g2g3/g.htm