Hello Sweden,
I believe Bengt is asking if he can bore out his master cylinder to 1 1/16" from 1" on his '37 and get parts.
Bengt, the filling station
http://www.fillingstation.com/ has brake rebuild kits but I don't know if you need to bore the cylinder out. Maybe if you call or write them. (if you want, email me, I'll write the question in English for you.)
Kanter's has rebuilt master cyliders for $150 US/ w exchange.
http://www.kanter.com/ There are probably other suppliers and I'm sure someone will know.
Jim