The gentleman and cyclist and cycle-collector organizing the BERGKÖNIG this weekend in Switzerland (!) has very kindly sent me links to some Allegro catalogs -

Swiss Bicycle Catalogs ? kickintonextgear

and Allegro Prospekt 40er Jahre &laquo Veloklassiker.ch

Hopefully, more information will emerge about Allegros - they are apparently heavily featured in this year's event!

edit - don't miss this one!