The V10 wouldn't work out so well becaus it would make the Raptor too nose heavy and wouldn't allow it to fly flat over jumps. Also it would be much harder to keep it cool without the giant radiator that comes in the Super Duty and there would also be less air flowing around the motor to cool it by convection. On top of that, it would probably get single digit fuel economy numbers, which hurts Ford's CAFE and would probably also effect sales some. The 6.2L Boss is replacing the 6.8 Triton V10, there's no way around that. Sorry if that bursts your bubble:shar:.Ford could have put the V10 in the Raptor.
It is roughly 4" longer than the V8. There's plenty of room for it.