Well, since whatever you connect as a feed to the battery has to pass through the alternator, which usually haas a diode based regulator attached, I would have thought you have fried a few didoes in the alternator. I doubt that the reverse on the battery would have done anything; however, if you then tried to start the engine afterwards without checking the alternator, there's a good chance you fried your electronics by a big, unregulated over-volt when you started the engine again (possible without the regulator). Sorry, it's bad news, I would have thought...

One of the few remaining Mk1 owners... #00015