you should place the pump and filter as low and as far to the rear of the car as you can BUT place it up inside the frame rails if possiable so its protected durring any potential crash or accident, ellectric pumps push fuel far more effectively than they suck fuel but they do suck fuel over a short distance just fine if the tank pick-up line and sock screen is mounted low in the tank, and IVE yet to have a problem if the lines are the correct size for the application, yes that usually means the pump and filter are at or slightly above or slightly below the frame and yes the tank might be lower, it usually has little or no effect as long as the lines are of decent internal dia. and clear and the pick-up tube and sock are in the tank sump


btw its also a good idea to use rubber mounts and a decent bracket to mount the pump and isolate the vibrations as many electric fuel pumps are noisy, and use double NYLOC NUTS or use wire tie nuts on the bolts with rubber bushings and large washers to prevent the mount bolts from comming loose due to those vibrations