Hi bicycle historians:
FWIW,I have a Claude Butler with brazed fittings for Cyclo Oppy that has
fluted seatstay caps just like Masi.The famous Mike Knepp pointed that out to
me back around 1990.The Butler would be from some time in the forties,because
the Oppy had a pretty short life.
Seth Finkelstein in Santa Cruz,CA-pieces of bike in every room!