A mechanical pump was a no-go on mine, that area gets really tight with the steering box. I used a $40 Mr. Gasket electric fuel pump mounted just ahead of the tank on the frame rail. I did run the main power through a inertial kill switch and a mechanical toggle switch (makes it handy when you want the carb empty to work on something)
The '86 Mustang GT ran the E6SE heads with an HO cam, it was rated at 200hp. I have an HO cam to poke in my E6 headed engine this winter.
While you are there I do recommend running a shorter front dress, Explorers are really common in JY's around me, although the pesky timing covers give fits as far as removing, it is hard to find one without at least one bolt broken off and you have to rip half the car off to get to discover this. I have done two and have resigned myself to paying the $100 and not have to do it again.
One thing I like about the Explorer is that the alternator bolts on from above, so if you are out of town and/or in the middle of nowhere it is three bolts and two connectors to replace the alternator. With the long pivot bolt that is mounted even closer to the radiator you have to pull the radiator to remove it (depending on set up of course) and then for my truck it is a domino effect, you have to remove the fan from the radiator, then remove the tranny coolers to remove the fan and remove the grille and offroad lights to get the tranny coolers... all for a stinkin alternator.
Basically with the Explorer setup, you only have to pull the radiator for the water pump or dampener pulley/timing cover... which is fairly normal IMO. The alternator and power steering pump are mounted nice and high and are easy to remove from their brackets. The Explorer also has something like a 130A alternator...