I Have a Problem With My 1975 Plymouth Duster

It is a 225 slant 6 auto. There was an electrical issue going on leaving the light on even when there was no key in the ignition(windshield leak is a probable cause for the issue). Plus I could not start the car by turning the key, I had gone straight to the starter to turn it over and it turns over (I replaced the starter when I bought the car). So I started replacing some of the old electrical components, (headlight dimmer switch, starter relay, starter resistor, and a few replacement electrical components and the problem still persisted. So then I decided to pull the gauge cluster out and found my on/off/driving light switch was corroded and a few bulb sockets were missing. Replaced those reinstalled my gauge cluster to which I know I can't even turn the car over and the lights that previously worked didn't. So I am a little stumped and was wondering if anyone has an idea to what maybe the problem. All help greatly appreciated! Thanks in advance.