I've always had a liking for reverse trikes, those morgans look pretty cool, the blackjack too, love the styling. This would be my choice for an electric conversion:
http://mevltd.co.uk/images_vehicles/tR1ke_05.jpg
You'd have to do something to improve drag though, exoskeletons and exposed wheels would most likely need to be covered in some way, but the weight including a yamaha R1 motor is only 350kg! Would be great for around town. If I lived in the UK with your high fuel prices and big kit car market I'd probably be working on one right now.