Always...
It's either going on top of the quarter, ala Charger, or more likely on the deck-lid filler panel toward the middle of the car. At 6'6" and a 5" ride height to the frame, I wouldn't have a problem at all reaching the middle of the car to pump gas.
Put it in the middle of the filler panel.
At 6'6" I take it the car won't have a back seat anyway could you move the engine back more?