Here is an original MC Gregory "Master" model alto mouthpiece stamped 618M. This piece measures .065" on my gauge.
This mouthpiece came in with the other Gregory we have here and has obvious signs of use. It came from an estate of a woodwind player in Toronto and can have the tooth marks filled in. There is no wear to the table, tip, facing or baffle though so it's a good chance to get one for a lower price.
This design is classic as is but also is a good candidate for a very focused and modern sound if it were to be opened up.