Jaguar: Back to the Future.
 

Check this out, especially the last few minutes.
https://www.youtube.com/watch?v=610Amyhpzzk

Another great informative video from fully charged. If I were restoring an old car, I would definitely consider an EV conversion, especially if the entire engine needed rebuilding anyway. Battery and motor costs are still pretty high though sadly.

The idea of having a unit that just fits in place of the engine and gearbox is a brilliant idea. If Jaguar ever gets round to marketing the unit I bet the price would make your eyes water! It is an idea that a third party might be interested in building and selling though.

I think the price of a normal E type would make your eyes water anyway (fully restored) maybe having an electric power train won't be so bad.

The great thing about that power train, if they ever produce it and sell it, is it is a retro fit for every Jaguar that used the XK6 engine. Everything from the XK120, through the E Type, Mark 2 (Inspector Morse), Mark 10, and even the Daimler Sovereign. I can imagine 3rd party restorers going mad for it. And it is a non destructive modification.
Other companies could do similar things for any marque of car that had a long running engine type (Mercedes, Ford, BMC A and B series). The list is endless.