Short circuit 63 Dodge Dart

Hello fellow A body friends.

I am seeking help with a problem with which I have very little understanding.

April 1rst (Some April fool's day) I crank my Dart and pull it out of the garage.

Sometime later, I roll it back and shut the garage.
Last week, I came to use but the battery was dead. I recharged it with the negative post detached. When it came to reconnect it, it sparked. I check to see if any accessories were on.

I tested with the horns disconnected (the only accessory I used that day). I would still spark.

Disconnected the alternator (which indicated charging the last time): still sparked at the battery terminal.

I unscrewed that red wire that attaches to the multi connector on the firewall: no more sparking.

Need to specify: I placed a 20 amps fuse between the battery terminal and the connector: it would fizzle and pop. There is that much sparking.

It is a restored car. The dashboard was disassembled and all the wiring verified.

Can it be the ignition switch, broken and shorting?
The red wire that enters the cabin, does it have any functions that distributes returns to the engine compartment?

Say the short is on the convertible top wiring, when I put the connector to the battery terminal I wouldn't necessarily hear the motor whiring (bear in mind that it has an integral circuit breaker) ?

Say the short is on an accessory connected from the fuse box, wouldn't the specific fuse blow?

Back the horns, could it be a wire inside the steering column shaft?