Hey up RR.
The 276 carb for the 1951/53 A7 is listed as 276EU/1DB.
The 276EU is a carb with 15/16 bore, a 4/061-140 main jet, a 4/061-107 needle jet, needle at number 3 position, 6/0524 throttle valve and a 1DB float chamber.
The 1DB float chamber has a standard arm and is mounted on the right hand side at 7 degrees. It has a bottom feed with a banjo connection.
Hope this helps.
Beezageezauk.