Voltage regulator smoking?

The voltage regulator failed, and what you have in the gauge cluster is an ammeter, not a voltmeter. The way it's wired the full current from the alternator goes through the bulkhead connector and through the ammeter. With the voltage regulator failure, the alternator output went straight into your under dash wiring, so, more then likely you've melted some of your under dash wiring.

Trace the wiring from the ammeter under the dash back to the bulkhead connector and then the other direction into the dash harness. You'll likely find something in that path that's melted.

It looks like there's been quite a few modifications to your wire harness over the years, which isn't uncommon at all. These cars didn't have all that many circuits when they were built (didn't need them). Unfortunately it's probably time to look into a new wire harness, because even if you find some of the melted wiring that caused the smoke and electrical smell there's probably more of the harness damaged than that.

It doesn't look like @67Dart273 has chimed in yet, he's one of our resident electrical experts and he may have some more specific advice for you on things to check. I'm not particularly great with electrical stuff and I don't know the early A's as well as the 70+ stuff.