You could ask Taff the Horns.... also.
He has a wide range of everything, I got a 12 volt coil and shim gaskets for a 1949 Altette off him, he has plenty of other horns tucked away.
http://taffthehorns.com/
Hi there.. I need a set of clearhooter lucas 9h horns for my triumph Bonneville T120r year 1970.. anyone may suggest where to look at? I recall Burton Bike Bits had nice repros and was providing also the spare domes, but they are not anymore available.. Thanks for helping!