Aldive did the most with his SOHC, he was after fuel mileage with the few power upgrades possible. There is a balancer available with a slightly smaller pulley size, it was about $260 when I bought mine.
Look in his thread, he upgraded the TB about 5mm IIRC, and I did that with also having it ported by a user on eBay who used to port many OEM TB's.
The factory shifting is a little lower than what's possible, 6000rpm is a good little step. But that takes a tune, not cheap. Everything is expensive top upgrade these things, the power gain is really minor versus the costs.
With those taller tires, near 32" you posted, it needs 32"/30" more gear to put it back to stock. Almost all 4WD models had 4.10's, I'd go at least one step above that, and two wouldn't be terrible on the street, if you want acceleration.
The E-fan didn't gain me any fuel savings, and there was no extra power felt.
The SOHC is a very frisky feeling engine in the 2nd gen Explorer, but the bone stock 302 pulls beats it off the line easily. The 302 loses ground right after the V8 trans(4R70W) shifts into 3rd gear. The 4R70W is a wide ratio trans, but what that really means is that it has normal gear ratio spacing between 1st and 2nd, and 3rd and 4th. The wide part is the big gap between 2nd gear and 3rd, the rpm's drop notably when it hits 3rd gear. So the SOHC begins to catch the V8 when it's in 3rd gear.