Awesome writeup and it's good to see the truck is treating you well. I had a 2002 F350 powerstroke and the throttle pedal went out on me, but it wasn't a limp type failure like yours, mine was a light switch failure. Literally stopped working while I was driving, I was heading down a pass on I5 in Oregon and when I went to give it fuel, I got nothing. It's always been in the back of my mind with the Chevy, but yours is the only failure I have been able to find. There are numerous LBZ trucks with 500k+ on them and no one ever mentions having to replace the throttle pedal.
Jack