Caliper Mounting Bolt Spacing
H series = 54mm
S series & all KH = 72mm

Master Cylinder ID
Dual Disc = 5/8"
Single Disc = 9/16"

Euro Master Cylinder has opaque plastic bowl... US spec is metal.
 

Master Cylinder '72-'77 (all Triples (US version))

Round Master Cylinder

KH 250/400  '78-'80 Master Cylinder

RH H series Caliper

Brakestays