It may well be possible to substitute a Euro-code lens on USA spec reflector if the car is a late enough model to have come with H-4 bulbs even in the USA versions, but earlier models which used the miserable USA type 9004 bulb are designed for the system of low beam optics which became obsolete in about 1955 but was still required in the US until the early 90's. Swapping a Euro lens onto a reflector with a 9004 bulb (or most USA lenses onto a reflector with an H-4 bulb) will produce useless and dangerous low beam patterns in most cases. I've done a number of experiments of this sort, and it doesn't work at all.