A firm in the United Kingdom by the name of Lunaz is taking old, run-down classics, stripping them to their bare metal frames, and rebuilding them with battery-electric powertrains. The Silverstone-based company started with a 1953 Jaguar XK120, and then followed it up with a 1961 Bentley S3 Continental Flying Spur. Now it’s working on Rolls-Royce…