Very Stupid Question about Euro Lights

Lenses are unique for lhd and rhd.. the idea being they are less likely to blind oncoming drivers

some are subtle changes to the spread pattern, some are made with a bias to aim down at the corner

Okay, that definitely clears up my confusion with the lense difference then. But does that mean I shouldn't do a swap unless I get LHD lights? I mean, I'd assume if I upgraded my lights to xenon it'd be just as bad if not worse than the RHDs…

Not a dumb question at all. The head lights on our Z's dates to 1930's technology. The lights are 6054 (200mm) sealed beams set by DOT to 65Hi/55Lo watts. What you are looking for are conversion lenses to utilize new technology i.e. 9004, H2, H4 bulbs. HID lights are another story.
"Pilot", "Rampage" and "Hella" make conversions for our cars. All avail on the net.
I chose to use Hella lense kits which I got from www.classicgarage.com. Kits were complete with 65/55w bulbs but I also bought a set of 100/80w ("off road" bulbs to fit). I use only the 100/80 and have had zero problems blinding others and no hassles from the fuzz.

Should you go this route, I recommend using "headlight pigtail adapters (Dorman $5.00) etc. The new halogen lights are hot and tend to cook our old wires. The changeover is simple (except for the rust)

86na
88t

For what it is worth, I wouldn't hesitate to put RHD lenses on a LHD car. Simple fact is that even with stock suspension, a Z31 sits with the headlights of most vics on the road right at eyeball height. So the chances of you blinding oncoming traffic with RHD housings and a non-HID bulb are pretty small.