[rotary rocket]

I would personally not do the option where the motor is over the batteries. I did this in my conversion due to space. The problem is the heat of the motor will cook your batteries and vise versa.

Also I would advise to put the batteries in the back and not the front. You WILL need the traction... The disclaimer to this point is glassdoctor's comment about the very light 4s 4000 packs. I use 2 each 2S4P 8000 packs.

The buggy will handle like a charm. The batteries are totally on the chassis (very close to the mid line of the chassis), and the weight of the motor is centered also. You can feel the "torque steer" of the motor though. Yet another reason to put the motor on the chassis like your second option.

If you go with this option I would swap the position of the motor to the other side to minimaize the torque force of the motor. The rotational torque will be towards the center of the chassis, and not towards the outside (left side).