My "new" '74 Duster- or why I need a project like a hole in the head

Jarlaxle said
The threads are long on advice...short on data. I need to replace my lights (lousy Amazon LED), and am reluctant to drop $700+ without hard data.

Even if you must have LEDs, you don't need to spend anywhere near $700+ to have worthy headlamps. Here's a good one, and here's another good one—for less than half of $700/pair.