Simpson's use of a Masi is mentioned by William Frothingham in his biography of the rider "Put me Back on My Bike."
On page 25 of this great biography he details not only the Peugeot badged Masi but the homemade saddle Simpson created from his wife's old crocodile handbag. Sound like a Unicanitor covered in foam and croc skin.
Brook Watts
Longmont Colorado USA