I'm glad it worked but you got lucky. Stop doing that.
That = When there is a failure that is causing smoke, do not just hook up the battery and turn things on.
Think of those two wires as battery wires - because that's what they are.
When there is a failure find the fault. Multimeter and test lights are your friends. If you have to live test then a light bulb or a circuit breaker (flasher signal) will help protect things.
Great!
I didn't read that you never had power in the car.
The ammeter is not a module. - although now seeing the circuit board I have a suspicion about yours...
Ammeters on these cars (up through '75) consist of a metal plate with the studs pressed into it. Fiber washers etc (depending on the dash) are used to insulate the plate and studs from everthing metal. The electrons moving past the needle create enough magnetic field to cause the needle to deflect.
this is the back of the ammeter used in the rallye dash.
View attachment 1716268560
In the photo of your panel - that looks to me like a replacement circuit board.
The ammeter should be attached with real nuts - not the stamped metal speed nuts.
If the connection is poor because the nuts aren't tight - that could be a poor enough connection no substantial current could get through.
While you have it out, make sure the studs are not coming loose from the brass colored plate. Loose studs are no good.
Another possibility is that someone thought they had a better idea ard replaced the ammeter with a voltmeter. A voltmeter can not be placed in line as it is essentially a big resistor.