My ‘69 does not have an under dash light but I did replace my guage cluster bulbs with LED and that helps a lot at night. The rest of the dash is like a black hole at night. This thread got me thinking that since I added a two USB plug to my dash that these would work for me so I just ordered them!
Febrytold 2 Pcs White Universal Mini USB LED Car Interior Ambient Atmosphere Lights for Car Interior Trunk Ambient Atmosphere https://a.co/d/g98qsnE