Regular gasoline cars run fine on unleaded gas, so no conversion kit was needed. But you are right in being skeptical - it wouldn't make sense to convert a gas powered car to electric. You wouldn't just swap a combustion engine for a electric engine. You'd need to change everything - engine, transmission, gas tank, air conditioning, dash/info center. And then you'd want energy recovery, so you'd change out braking systems. Best case is you'd end up with a heavy, expensive, inefficient, poorly balanced electric car.
The rest does sound quite plausible though. At best one would end up with an improperly balanced car from the difference in engine weights alone unless pains were taken to ensure the car's weight and weight distribution stayed the same.
