I also had a '77 Spitfire as well (50th anniversary of the Spitfire, BTW). Did not have much trouble with the electronics, but the ignition system was previously replaced with a non-Lucas kit. Of course, I did have to replace the master and slave on the clutch and the master on the brakes - I lost half the brakes coming back from Malibu on PCH. I never stepped so hard on them in all my life. Fortunately, the girl in the car with me at the time never knew the difference.
Some other Spitfire humour:
Little Billy and his Dad were down at the autocross watching the Spitfires zipping through the cones. Little Billy looks up to his Dad and says, "Dad, when I grow up, I want to be a Spitfire driver." His Dad looks down at him and says, "You can't do both, son." Q: