There is no standard for whole plate holders; there is considerable variation in both antique and modern holders. There have been several discussions of this over on the Large Format forum, most recently:
No... I have several whole plate, half plate and quarter plate cameras. None of them have compatible holders - each is unique to the camera. There may be some sort of standard for the sheet film or for glass plates (but I wouldn't be surprised if that hasn't changed over the years or existed as different standards in different countries or for different purposes) but definitely not holders.
I wasn't sure if there had been an ANSI standard set for the size or not. So, I guess not!
Next question: I have a Century Model 46, full plate, ca. 1907-15. Anyone know what the dimensions for their holders are? (And, yes, all I need to know for now is the outside dimensions -- my back is damaged and I want to fix it, but I need to know the dimension mentioned in the original post to fix it.)