Darn it, all this pontificating and I wasn't the pontificator, lol. I think Plymouthy is just trying to give a heads up to the unwanted issues you might run into. But I will say this, last inspection I had did not include the required road test, inspector couldn't drive a three on the tree, lol. Furthermore, it would take a really sharp cop, these days, to notice the headlight pattern and pull you over for it.
That said, years ago I had a second shift ob that left me driving thru about 40 miles of dark, two lane country highway going home. My hi/lo headlamps were E codes and my hi only head lamps were aviation landing lights, 87 Diplomat 4 rectangular headlight setup. That sufficed unto the day, lol. Legal? Nope. Useful, oh yes,
I have a thing about stupid laws and mandating DOT spec lights is one of them. Now my 51 does have DOT compliant LED headlamps, true, designed ones, not a retrofit. Not cheap either.
But one issue I do have with all this commentary is that many of our cars were built well before the DOT put it's two cents in and never came with DOT compliant lights. Not sure the law applies to them. Kinda like seat belts.