(There is a #00, smaller than the #0, very seldom encountered.)
Proper hole diameters for these are:
#0 - 34.8mm
#1 - 41.8mm
#3 - 64.2mm
Note that the holes are larger than the major diameter of the shutter mounting thread, and properly so.
The retaining ring has a lip at the rear (facing the lensboard). The mounting hole must be larger enough to clear that lip.
You may encounter shutters mounted incorrectly, in holes sized for the thread, with the ring reversed (lip on the outside).
Note that many other hole diameters were in common usage for other shutters. Sizes were not at all standardized.