I doubt if I can answer all your questions, but I can tell you what little I know (and hopefully, someone has experience with this mod on an Explorer). I had a '90 Mustang LX 5.0. Magazines put it in mid-14's stock, which is pretty quick. Keep in mind though that that's with factory headers, roller cam, and dual exhaust. I'm pretty sure that with some reasonable modifications, that 225 HP engine could easily reach 275. I'm talking bolt-ons like intake manifold, larger throttle body and MAS sensor, better headers, free flowing exhaust and high flow cats. That is enough to get it into the mid 13's in a Mustang. But, keep in mind that a Mustang of that era only weighed about 3200 pounds; an Explorer weighs 4000-4500 pounds.
So, I'd say that with maybe a little extra cam, and a high stall converter, along with 4.10 gears (limited slip is available in many forms for the 8.8" rear end), you could get that Explorer down there. As far as bolting up the C-4, look at advanced adapters. I'm sure that the C-4 hooked up to the 5.0 in some vehicle or another over the years, so that part shouldn't be hard. Adapting it to the rest of your drivetrain may take some fabrication, though. (My friend's brother used to race Mustangs, so I've seen the results)
Of course, with that much power, you may want to opt for a tougher tranny. The C-4 is a lighter duty transmission, though it is used quite a bit in racing (probably its light weight, and there's lots of them around). I don't know how the newer A4LD and such compare in strength. Hopefully, someone here with a V-8 Explorer can give you more insights into making this work.
Take this advice with a grain of salt; The only engine I modified to any degree was a 2.3L 4 cylinder. Cam, header (only one), and a bigger carb primarily. It was pretty quick, but was weak at low RPM's. Would rev right off the tach, though. Dead Link Removed
Check Dead Link Removed for the multitude of parts available for the 5.0. They have a whole section in their catalog for that.
Oh, one other thing, a tall intake manifold will not fit under the standard Explorer hood. Some of those performance manifolds are pretty tall. Also, stick with fuel injection, don't go carb unless you are going to go all out. They're a pain compared to injection.
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Tom
99 Sport 4x4
SOHC
Auburn Rear & Gerald's old Shackles
