Power sometimes

Good morning all
Looking for some trouble shooting help my car is a 1970 340 duster auto and I seam to have power sometimes dome light door buzzer even enuf to start then once the car is off I have nothing until the next day
I have replaced engine to batterie ground and am planning a optima batterie to help with the fans and fuel pump etc
I want to do the mad bypass but would like to have the car in running order before I start any help is greatly appreciated
Pic of my baby