While I'm a huge booster/fan of oil additives, especially for keeping internals clean and cleaning up mild cases of PO neglect, I've always been skeptical of using anything like that in situations as severe as yours.
Not speaking from experience here, but it you rely simply on the cleaners, you could dislodge more and bigger pieces of the stuff in a situation (running engine) that is not a good idea.
Now, doing it AFTER the initial cleanup, that's a great tool. But doing it as the cleanup, maybe not so much.
Again, no direct experience. Just thinking out loud and wondering what others have experienced.
As far as the rockers, I'm interested too. Haven't searched yet, but if they're non-adjustable "set it and forget it" types, then yeah, that's about all you'd have to do. Other than verify the number of turns or the torque, just to make sure they're still in as-specified condition per the manual.
It's usually considered a good idea to still run the bolts out and down when the rockers are at their cylinder's TDC compression position, but it's probably not an absolutely mandatory step.
I just don't like the idea of removing or reinstalling a rocker when it might be under full-open tension, is all.
But that's just me. And as I said, I'm not familiar enough with all the ins-and-outs of the 4.0 to dispense forth. Just talking and uttering what my experiences have been with other engines.
Hopefully this just keeps it up near the top where some experts in 4.0 valvetrain work can pop in for comment.
Keep the pictures coming during the process too by the way!
Love to see the results of your work.