Electrical issues

I need help tryin to steady the voltage. Its a 59 ford galaxie and it is running very unsteady. The dome light flashes the head lights flash the radio pops. It seems to be a ground issue but i have a ground from the engine to the body and i have ran grounds from the engine to the frame and even from the negative battery terminal to body/frame and it makes no difference so maybe not a ground issue. I have wired the radio straight off the battery and it still pops and i know the radio is good and it works fine when the engine is not running. I have ran the car with the generator belt off with no difference so it isnt the generator. I have 2 condensers on the voltage regulator and they make no difference. I replaced plugs, wires, cap, points and condensor. There is also a small miss in the engine and 2 cylinders only have about 60 lbs pressure but it is a 292 and people claim valves cannot get tstuck on these. Any ideas what else i could try give me any ideas.