One danger of running the electric pump through the mechanical is the danger of rupturing diaphragm in the mechanical and mixing gas with the oil. There's really no "stock looking" way to get around it since it needs a shuttle valve in the line. A high-pressure pump isn't available - as far as I know - for our old iron.
The electric pump should be placed below the tank and as close to the tank as possible, hence the location under the car. And, since there's more room for it near the rear end ...
Wire the electric to the key so that you don't get surprised on the first freeway on-ramp you hit.
