In the days when 427 S/O thundered beside 426 Hemi cars, they were turning 7000 to 8000 rpm. Maybe a tad more. I saw a 428 spin a rod bearing short of 7000 (in a second) back in the day.
Today many FE are going to large strokers and people just do not turn them that high. Many improvements are now known, and I think a center oiler will servive in the 6K range quite nicely. I have my doubts that a factory block center oiler can live in the rpm range that a S/O can go to, but it is a moot point for the big strokers. With that type of money not too many are willing to push them to the limit. However a priority main
oil system like a S/O is no doubt better. At least in my mind.