Welcome to AF. I'm on my 2nd scotch, so not sure how intelligent my suggestions might be??
1. Are you getting WOT in the cable operated throttle body?
2. When you're climbing those N.C. hills at WOT what does the Eng Temp gauge do? Does it stay the same or rise quickly?
3. As jCat mentioned above, fuel pressure and flow are pivotal for producing power and rpm's.
4. Check for intake restrictions, Mice, Birds, Moose.
5. Make sure the ECT is providing the correct temp to the PCM.
6. Give my regards to Jr.