I have supplied a few chassis to a training centre who have put 2 very large electric motors running through a type 9 in to a tiger chassis. The only problem is that for every 5 miles of driving you need to carry a 5kg battery which takes 12 hours to charge. Have you considered using a small NA diesel with a turbo? Don't use a turbo diesel just a NA with an added turbo, this means it has smaller injectors so good for economy but burns the fuel more efficiently. You could always get one of those under car mounted speaker sytems so that you can mask the diesel rattle
