The problem is you need the motor to have the spinning side a certain way in relation to the drivetrain. The old XRay (Tamiya 414, etc.) was fairly balanced, but like many designs of that era, in order to still have batteries on left, your motor will either have to be far back (not good for its swing pendulum weight distribution) or high up, which isn't good for center of gravity. There have been all sorts of designs in line with what you are thinking, but they just don't seem to work for road racing, so they were abandoned. Now for oval that may be a different story since asymetrical layouts are fairly common.
RC Car Action Editor and Photographer