Well, I have to say this from experience. Don't believe the hype. The 4.0 SOHC will last a long darn time. Every engine has its problems and some have bad experiences with a certain engine. They then vent their frustrations and it spreads like a rumor. That doesn’t mean your fate is a timing chain rattle in the next couple of weeks.
I have a lot of “abnormal” turbo miles on this motor with no problems. Maybe it’s because I change the oil; maybe it’s because I know when to say when….whatever the case, it’s lasted.
Proof
+1
Kinda like the Taurus 3.8L, and the GM Quad4. IF they were properly maintained by an owner who gave a crap, they would last. They just didn't tolerate alot of abuse.
To the OP. Yes, technically all SOHC 4.0's are the same basic design. However, Ford implemented some improvements over time to reduce the timing chain issues. I believe this was in '03 or '04? Maybe someone else can chime in on that. After all, they were still putting these in the Mustang until this year.
The SOHC can be built to perform quite well, fi you take your time, and do your homework. Just a SCT XCAL3 w/ some custom tuning will make a big improvement, and that's before you touch any "hard"parts. If you want a V8, go buy a V8 Explorer. Don't butcher another 4.0L one. First, save them for people who will appreciate them. Second, it will be much easier and cheaper for you, if you really insist on a V8, to just buy one with it already in from the factory. As has been mentioned, it's not just swapping motors. You'll also have to change the trans, as well as deal with electronics. In addition, there may be legal issues, depending on your state laws.
If you are willing to pull the motor to swap it, then pull it and fix it. Once it's done right, you'll be good for many, many miles, and years. Of course, this assumes proper oil changes,etc....