Why rear mount an engine that would easily mount under the hood? Besides the serious fabrication, and added expense, You'd lose enclosed space. You'd be in cab with a loud, hot, and stinky motor. You'd need a snorkel, or at least to run with the windows down, since a motor uses a huge amount of air. You'd likely need to cut holes in the roof, and mount the radiator, and fan outside. Your center of gravity would be considerably higher. Your front drive traction would be nil. You'd need custom heavy weight leaves, and ligher springrate coils up front. Power brakes would be difficult. You'd need a huge hole cut in the floor for the transmission which would be hard to seal dust out. Off the top of my head those are a few things to make it not worthwile. I'm sure while trying to tackle something like that a whole other host of problems would arise.
The only pro I can even almost justify is that it would be "different" To me for the money and work involved you could do somethign a lot more practical/cool.
