Where to mount in-line fuel pump?

[5.0 Fiend]

I have my car pretty much finished except for engine/trans lube, steel gear for the dist., and mounting my Holley red fuel pump. I have the relay and wiring all ready, (mounted in spare tire well), but now I need to mount the pump. I was underneath the car last night installing the driveshaft, and I was looking for a place to mount the pump, and I couldnt see a good place, a while back some suggested to mount it to the frame rail, but I couldnt see where it was, (I'm use to looking at the frame rails on rigs, maybe the mustang rail is tucked up in or something). Which side would the fuel lines be coming from the tank, and where should I mount the pump exactly, (give me specific locations, like here by the fuel tank or something), also why are there 2 fuel lines up in my engine bay, the car had a mech pump, and I only remember on line going to the pump, then one line going from the pump to the carb, (breather line? retun line?).


Also, does the oil pressure fitting fit on the front of the block by the timing cover? (the 84 engine used a mechanical gauge, and the 88 motor appears to have a white electric fitting stcing in the block by the timing cover, is this indeed what it is? I cant find where the mechanical fitting would go, and the electic one wont come out, so I am probably just going to buy an electric gauge if need be.
Any help would be greatly appreciated, thanks.