This thread is a couple of months old, but just my $0.02...
The different styles of mirror have differently shaped pieces of glass.
I do not think that simply getting a new piece of glass cut will fix the problem with JDM folding mirrors, as it is the housing that requires adjustment.
I am unsure of how to do this properly without damaging (rounding) the screw located on the bottom of the housing.
I think the difference in all RHD and LHD folding mirrors is the angle that the housing is fixed at. The driver's side mirror (even on current USDM cars) is fixed at a more outward angle than that of the passenger side mirror. Look for yourself and see. My Maxima has manual folding mirrors, and you can definitely tell that the angle of the LH mirror differs from that of the RH mirror.
I have JDM power folding mirrors on the MA70, and am of the belief that if I could adjust the actual RH (passenger) mirror housing inward a degree or two, that the optics of the glass would be fine and I would be able to see out of it with no problem. And, it should also still be adjustable. Short of that, I have considered getting a new piece of glass cut for the passenger side, and using a custom wedge and double sided tape to achieve the angle I need. I think I'll just stick the new glass (and wedge) directly on top of the original mirror glass, unless there's not enough space for it to fold or adjust afterwards.
Anyone else have any other thoughts on this?