Do you understand that you'll be ruining your headlights? For one thing, the optics of the JDM lens are designed to work with the optics of the bulb and reflector in the JDM light. They'll still kinda work, but the amount of light coming through will be very small because the 9004 bulb sucks compared to the H4 bulb. So you can't get good light out of a "frankensteined" headlight like that.
Perhaps a more important concern, though, is that the beam pattern of these lights is primarily determined by the lens. By putting RHD lenses on, you'll end up putting light in all the wrong places.
There really would be no possible way to be able to see with your proposed setup, especially (but not only) without blinding everyone else.
You'd probably be just as well off with your high beams on all the time.
Please, please do not cup your hands to your ears and ignore what I am saying.
"Just reading vrg3's convoluted, information-packed posts made me feel better all over again." -- subyluvr2212