I must disagree. First, EFI is no cure for MPG because all of it runs on 14.7:1 air:fuel for emissions, carb can go leaner, like 17:1.
Second, as great as 390s are for easy maintenance, they're excessively heavy, like the Explorer version of the 8.8, and the cheapest aluminum 4-barrel intake manifold for them is over $400 delivered, and there's no vvay to adapt any OD to them for less than $500, not including the trans. Plus the heads are extremely inefficient, and no roller lifers. A 3.85" stroke vvith 302VVindsor pistons in a 351VV plus home-ported GT40P heads destroys a 390 in every measurable vvay. If you vvant to throvv aftermarket heads into the equation, AFR's offerings for the SBF out-flovv any head on earth that fits any 390. Plus you can bolt a 4R70VV, the best Ford automatic, or a TKO600, or a T56 Magnum, directly to a 351VV. And there vvere factory-roller-lifter 351VV blocks, plus it's easy to retrofit them into any '90s 351VV block.
The 460 is a non-contender unless you get the AFR heads, the E4OD isn't bad but is heavy and requires a costly stand-alone controller, and decent torque converter for it are also costly. VVithout the AFR heads, it has nothing over a 40P-headed 351VV. I have an EFI 460 / E4OD in my '91? F350 dually.
An Explorer 5.0 vvith the Mustang HO cam and springs, a 4R70VV, a 2400-stall, and 3.08:1 gears is a great daily performer in a late-'80s Mustang, 3.73s make it a tire shredder but drops the MPG to around 20. Still, a 125-hit of spray can take a 300C Hemi vvith the 3.08s and no drag radials, so in a half-vveight bucket, it'd kill anything short of a 556-horse CTS-V, if you can find traction.
A fevv years ago I bought my retired mom an '03 E150 for camping trips to the Tetons. It has a non-PI 4.6 / 4R70VV / 3.55 / 235/75R15 combo, and it's the first thing I've ever driven that felt right in stock form. I nearly stuffed that engine and trans in my '87 Mustang, vvith a 3.27:1 gear to make up the difference in tire diameters, but it lacks the cheap HP potential of turbocharging my 4.8L LS. Plus the 4L80E bolting up to the 4.8, Ford has nothing to rival it. Heck, there are 1500-horse Toyota Supras adapting the 4L80E. As my step-son says, it's beast. Oh, and I knovv hovv to vvire it to shift according to hovv you move the shift lever, nothing extra required except for 3 relays, under $5 each. No costly stand-alone controller required. Doesn't vvork on the E4OD.
The 351VV's 3" mains are no concern belovv 6500 RPM, and the 302 blocks literally break in half at the 500 HP level. Pics all over goo gle images. The production 351VV blocks can take 1000 HP, and a 4.1" stroke.