I use hardblock and won't run a stock block without it. Hardblock is magnetic because it's designed to heat and expand and contract like cast iron.
Oil causes Detonation, nuff said.
You have more oil then I like. I would check everything that controls it.
Sounds like the heads might need seals and oil drans if u can.

Your intake might need a surface cut if it's letting oil in around the heat crossover. I try to block all that crap.