Setting the idles and fuel/air ratio

If the idle changes in an unmanageable level, disregarding AC and lights, it may be an indication of poor tune, IE not enough timing advance, incorrectly adjusted carb, or other problems such as a worn engine or vacuum leak.

If the AC is too big a problem, you can "rig" an idle solenoid, activated by the AC clutch, which will boost idle speed with the AC clutch engaged.

So far as headlights, I don't see a problem. Many of these old cars dimmed lights somewhat, but this can be improved. It might be the old bulkhead connector problem, or other electrical problems.

One big improvement can be had by going to the later model "squareback" alternator used in the mid 70's which you can use with your old style regulator by simply grounding one field connection on the squareback

It may also be that there are other problems, such as a problem with the alternator (internal problem) that causes it to not output full current.