So. I'm in a wonderful position to review "stock" US DOT  headlights
(rectangular variety) against Eurospec (H4) rectangular headlights.

My 86' Syncro (the Goldbrick) has...or had until tonight) stock US DOT
headlights, with poor grounds, etc. When on, the headlights barely
illuminate the road.

My 91 Syncro Westy has good grounds (the US DOT headlights were
definitely illuminating the ground, but still left a bit to be
desired.) It also now has Eurospec headlights (and relays on the
headlights for good measure). The headlights are WONDERFUL. Bright,
focused light right where you need it. In the conversion process I also
took the time to remove the bulb from the highbeams, slosh some window
cleaner in their (followed by some isopropyl alcohol) and my highbeams
are nice and shiny now too.

I'm now back to working on the Goldbrick. I removed the headlights
(noting that one carrier of galvanized metal has a surprising amount of
rust...) Of course the adjusting screws on the Goldbrick aren't in
nearly as good as shape as they were on the Westy (and I still had to
replace one of the adjusting screws on the Westy that had been broken
by a previous owner.) I only managed to break 3 of the adjusting screws
on the Goldbrick headlights. Quite litterally the plastic shattered as
soon as I touched it.

Fortunately these are still available (and I'll be stocking up on them
real soon now). One of these days I'll come back to these remove the
headlights, bead clean the metal carrier and then put a decent coat of
paint on it, and then put all new adjusting screws on it. Should make
it last another 20 years.