If you listen to the Aero Deep Dive podcast, you will learn that aero is not a direct or 1:1 relationship.
Generalities may be true, but also false. Meaning that the “low and narrow = aero” is an oversimplification that is right sometimes, and wrong sometimes. Frontal area matters, but so does the profile behind it.
Sadly, without aero testing via a couple of defined methods, we are simply guessing and applying rules of thumb, which may or may not prove correct in any given instance. Likely, your drop of the bars may prove effective in reducing overall drag, but it is a guess at best without looking at the other implications of that change (i.e. body profile).