Tony - thanks for the how-stuff-gets-damaged assessment. While waiting on the used cams and bearing-caps, I got everything disassembled and inspected. Caps and bosses - except for the tore-up one - looked pretty good for 142K, at least I thought so. Chain wasn't side-to-side sloppy at all. Followers didn't appear to be marked up - just some discoloration - even the one that had that broken-off flange wedging the valve open (#1-intake, closest to the cam-phaser). I only used the replacement intake cam, and did a "fingernail" scratch test on the bearing journals on both it and the original exhaust cam - used narrow strip of 600-grit emery paper on each - counting see-saw motions 3 times around each one until they were smooth. Used an entire can of brake cleaner on/in each one to clean them, and another couple of cans on the head and chain. In the well next to #1 follower, I used a magnet to retrieve probably 1/4 tsp of iron bits. Got cams in, tensioner snapped in, oil changed (made sure chain got a good dose too), and then cranked it for 15-20 seconds to make sure oil was getting to the head OK. Cam cover back on - coils - and then cranked for a run. Happy to report the initial "stumbles" quickly disappeared and it ran smooth within a few seconds.
I'm just guessing... I found a Pennzoil filter on it - I know the kid would in no way have changed it himself, but I don't know what stop-and-rob quick-lube place uses those products. I noted that the oil that I was blowing out of the wells in the head, with the brake-cleaner, sorta' reminded me of the juice from prime-rib - little globules of fat swimming around - the brake-cleaner didn't really "dissolve" it as much as it just loosened it up and floated it away. The drained oil was also NOT 0 or 5W - anything - it was THICK, and could have very well been NOT synthetic. I'm guessing that was more likely the cause of this problem - too-thick oil, run too long, and maybe made from dead dinosaur skin instead of re-constituted "gas." Will change the oil after a few hundred miles, and replace with 5W-something and a WIX filter. I saved the old filter - will see if Hobo-Freight has a filter-cutter - would like to see what's in it.