at the moment I am looking at a 96 toyota tercel engine/transmission swap for the n600, other alternatives are/have been wankel powered rear engine possibly on a vw transaxel it would keep the clearance low in back but i am working with a sedan also, as far as no radiator room, it wouldnt be too difficult to put the radiator in the rear of the car (with electric cooling) by pulling the fuel tank and adding a fuel cell, plus all those metal lines running all the way back behind the car would only add to the extra cooling. if anyone knows of a smaller/shorter engine/transmission combo please post it or let me know, I am going to make this conversion in the next few months. and dont really want to put a motorcycle engine on a harley transmission :P