Wait, I found my flexitape.
I'll go with MM's dimensions . . hopefully that'll be everything you need.
Keep in mind, this is an ESB helmet (but really, are there any other's worth mentioning?)
A: 322mm
B: 156mm
C (Boba's Left): 125mm
C (Boba's Right): 135mm
D: 48mm
E: 375mm
F: 118mm
G: I Got Nuthin'
H: 179mm
I: 67mm
For J&K I assumed the line breaking the two dimensions was if you extended the line where the cheek meets the ear panel, if that makes sense to you.
J: 317mm
K: 462mm
X&Z I don't really know an easy way of measuring so . . not sure how much help I can give on that one.
Hope these help though.
Jer