If it was, it would be in the shop manual.
You have to consider that many of these old truck engines are well passed their normal service life.
Nobody wants to rebuild them, especially the 216, because of the expense.

If this is something that really bugs you, you could buy a used one to clean and swap out.


"Adding CFM to a truck will only help at engine speeds you don't want to use."
"I found there was nothing to gain beyond 400 CFM."