Here is the best solution that I found for doing this: https://www.summitracing.com/parts/mor-74107
The instruction sheet is on the site to show how to wire it in. There may be cheaper versions of solenoids, but I went this route knowing that Moroso made this for doing exactly what I wanted to do.


1963 Belvedere (mine)
1969 Roadrunner (wife's)