I recently did a 408 with a hyd. flat tappet stick , Comp steel rockers and oil through push rods.
I didn't restrict anything , but spent a good bit of time prepping the block for drain back , opening up the feeds to the mains to enhance rod oiling , etc.
High volume pump , scraper , big pick up etc.
It didn't appear to be drowning the top end while I primed it...
I did not enlarge any of the passages, but I did clean up the regular block casting openings, removed a pile of the rugged flash just sitting there. Cosmetic mostly I think, but easy to do once and at least it gives me a peace of mind.
Appreciate the feedback, thank you!
