"high-beam H4's" is not really logical, as H4 refers to a
replaceable bulb with two filaments.  I have a round light
model (with a JC SA grille about to be installed), and
haven't looked closely but I'd expect the square high beam
units (inner) to use H1, H2, or H3 bulbs and too indeed, be
the same as Euro units.  The simplest answer must be
installation of the Euro H4 outer units--I'm sure no grille
mods would be required--is the mounting bucket the same?