68 Valiant dies and runs lumpy, then suddenly runs fine.

"ALT' gauge goes wonky" ? They do need 12 volts to run right. Just brake lights can draw a faulty system down to engine failure.
So my question is.. do your headlights dim at idle and blare up with acceleration ?
ALT gauge needle twitch with turn signal operation ?
I'll add the following just because of previous responces to these questions...
How good the battery is and how well the starter spins really has nothing to do with how the rest of the cars electric works. The large wire from battery to starter goes nowhere else.
And by the way, Blowing compressed air into the fuel line will blow the sock off of your pick up assembly inside the tank.