That’s just it. It doesn’t fly. It’s wrong (speaking of the BBC example). It was done because they were trying to fix a issue with a big, slow, lazy port.
No half assed, semi competent engine builder purposefully builds an engine with ports that are far too big for the application.
Once you get your slow mind around that you may start learning something.
Said another way is in simple words because some have comprehension issues, you don’t ever build an engine with HUGE ports and the crutch it with a small manifold. It will be down on power by a wide margin compared to the same engine with the correctly sized ports and intake.
Arguing otherwise is just moronic, so I expect you to keep arguing for wrong engine building.
