Lights go dim and bright

That's not "just how it is". My '71 Valiant doesn't do that.

I think you have the older-style non-electronic regulator and alternator if it hasn't been upgraded already, and more often than not "cycling" lights point to something going on in the regulator.

I'm not an expert on these systems, so hopefully those with more knowledge can offer some help on troubleshooting and potential upgrades.