1964 Valiant Power Drain

My 64 valiant draws quite a bit of current when I run my lights.

To the point where it will die if I idle too long at a stoplight.

I changed out my voltage regulator, and that helped with the heat/radio/wipers, but the lights are still my big draw.

the battery should probably be changed, but it holds a charge no problem if the lights aren't running.

thinking it could be an alternator issue (or as mentioned, a battery), but is there anything else it might be? I am pretty handy with the mechanical stuff, but the electric side has me a bit concerned.

Thought I might post and ask before starting an unnecessary project. Perhaps it's a short in my wire somewhere? Is there a simple solution to diagnosis?