I have a 66 with 383 small block. It is a new build 3 years ago. I’ve had starting issues since. It just clicks at random times. Hot or cold. Here’s an example, Drove it last week and it started fine but when I got to my destination and shut it off it sit for probably 5 minutes and then just clicks. Had a guy with jumper cables and it started fine. So we unhooked jumper cables and let it sit for 15 minutes and went to start without cables and it started fine. Can’t seem to nail this down. This has happened several times at random. Have tried new battery and starter still does the same.