Hey, no problem - always good to re-check the mental checklist. Wouldn't be here if I wasn't trying to tick all the boxes with the help of the experts.
The Melling and the good lifters from the engine share the same size oil hole. The Sealed Power lifters I tried this morning were smaller, and the bad lifters from the engine are about the same size, but have that hourglass shape before them.
The engine is a 1989 LA 360 that came from a B350 from the junkyard, and was so clean inside as to be a unicorn find. Everything checked out perfect, and sludge was non-existent. This is what it looked like on Day #1 of teardown:
I have no doubts that the oiling is fine. I could swap all those lifters in the front of the engine in the video to the back, and the flow would go with them.