67 Barracuda Heavy Electric Load

That does not sound like an ammeter. Right after start up with an ammeter the needle should head toward C as the system recharges the battery. Either the gauge has been converted to a voltmeter, or the alternator is not charging to recuperate the system after the drain to spin the motor.
Its an ammeter. A Voltmeter would be 0 with the the engine off.
Unfortunately, its not isolated to just a battery any more. So now the current path is a muddle and the ammeter isn't showing flow from or to the battery.