Holy moly - there's knowing nothing about cars, and then there's the guy that put together the engine that's coming out of mine...
1. He thought it was a solid roller motor. Never had a reason to doubt him, since the lash settings were all consistent with what I'd expect to see for a solid roller engine. Well, it wasn't! So there's been an .018" air gap where parts were being hammered away, when it's supposed to have 0 lash plus preload, since it's a hydraulic roller...
2. He used the cheapest parts possible. The rockers are a notoriously bad offshore brand. About 12 of the 16 were OK, the other 4 were so out of round on the trunnion, you couldn't even rotate them a full 360 degrees inside the bore.
3. Due to some combination of the above, a lifter disassembled itself. The cheap lifters use a little spring clip to hold themselves together, so even if a pushrod breaks, they stay in one piece. Not so here, and several of the lifter internals are missing. Based on the fact that the distributor gear is chewed up, I can guess which hole they made their way down en route to the oil pan...
4. He never checked piston to valve clearance. Ever. I only pulled one head so far, but #2, 4, 6, and 8 intake valves have clearly been pounding away at the piston, so much so, that there are shards/slivers of aluminum sticking up in each piston. I would not be surprised if the valves are tweaked accordingly. #8 obviously had the exhaust valve also hit the piston. But the dumbest part? The valve reliefs are all chewed up in the same spot, meaning he bought pistons that had the reliefs sized for a 2.02" intake valve, but then put heads on it that had a 2.08" intake valve...
5. He never had the lifter bores honed, or never checked the lifter clearances. Three were so tight in the bore, it took vice grips to wiggle them out. Lifter body and bore were both badly worn for a motor that probably has a run time measured in single-digit hours...
I seriously hope this guy doesn't work in the Army's maintenance group, or there are going to be some tanks/Hummers that are disabled in the near future...