let me revive this thread with some added information.
Thanks to SOTW member Aldevis who mentioned this to me first,
I have found this, the Labanchi Clarinet Method ( download it all if you want here but be advised that it is in Italian and also, old Italian, and written in a very old style indeed , so even if you are fluent in this language you may have problems in reading it ( It is my and Aldevis mother-tongue so we have no problems with it even despite its stylistic variations with the modern version of Italian)
You can clearly see in the illustration that he plays with the mouthpiece upside down. You may think it is a mistake of the draughtsman but this is NOT the case, in the description Mr. Gaetano Labanchi says that you can play clarinet in two ways.
With the reed under and the reed above (!!!!) By the way, he calls the reed " Linguetta" instead of the more common term " Ancia". The reed of a mouth-organ or harp or accordion is called " Linguetta" in modern Italian.
Anyway Gaetano Labanchi says that playing with the reed above is way preferable to playing with the reed under because: " the voice expands more, and you can thin the sound to the point that it resembles a distant echo"
Also he says, that you can " tongue" more precisely this way and that the instrument is more freeblowing.
Labanchi, in his preface, writes that the clarinet student has to have good physical condition, he has to be of some musical disposition as well the " Letters" (he means that one needs to be acquainted with reading and writing prose and poetry) and that he needs to have well formed lips, preferably with the lower or underlip slightly bigger than the top.