Lathe is a "Lansing G40". Imported by S&S in New York. Gornati has some parts and manuals. I think they may have built some of the Lansings. Gornati has a brake assembly for 1900 U.S. dollars.
Found a very similar brake(dimensions within 2mm of mine) at MWM in Milano. Not sure if part is available anywhere other than MWM, or price they want.
FWIW, the MWM model number is EBLF 140, Code: 05.07.140.01.