Well, here's an update for you: just killed my Beta.
Obviously the new assembly from Italy isn't going to work (could it be for a Trevi?) so I went back to a local donor car that's about an hour away and harvested its assembly. It's a 79 and mine's an 81 but the connectors look identical, so what's the worse that could happen, I say?
Well, this: I get the latest assembly installed but haven't put steering wheel or steering column plastic back on, just want to test it to see if it works, and I have apparently killed my Beta.
Put ignition key in, and the irritating jangle of the keys-in-the-ignition chime starts but nothing else: no lights, starter, signals, instruments, nada.
I've charged the battery all day to make sure it wasn't just it being low, so I've definitely done something bad. What did I do?