It is so hard to believe that someone with the taste to appreciate such a fine car could also not appreciate how wrong it would be to steal it from someone. What are you going to do about the missing VIN plate? Without it, how did the cops trace it back to you?
It is so great that they did. On my 122 I had the key code and was able to go to a "real" locksmith and get a key made from that code. He had a book to look up the code in. I can't imagine that there would be too many different codes to try but I guess we don't know what year the coil is from. I am surprised he didn't just put in a regular coil with an aftermarket switch to at least get the car home. Trying to carry that coil with the long armored cable sticking out of it doesn't seem too incognito...
On my 122 when I got it the original coil was still in use but a afermarket switch was adapted.
I bet a good locksmith would be more willing to help if you could take the whole assembly out of the car and bring it to him so he could work on it on his bench. That way he could work on it at leisure and it would probably be cheaper. You could ask the price and then ask how much less it would be if you could bring it in removed from the car...?
It is worth finding a good locksmith as from experiance their competance and dedication varies quite a bit. maybe the locksmith that posted can tell you how to identify the better ones. Also maybe someone on the board knows of a good one in your area.
Good Luck.