Oiling system pitfalls?

Relative to the SBC's... the SBC oiling is distributed through 3 different passages. The SBM oiling is all distributed from one passage (passenger side gallery), and some paths are much longer, so the SBM setup has more ways to have issues.

The HV pump will flow a bit better at lower RPM's, and can make better use of a higher pressure relief spring; any better flow at high RPM's is engine internals dependent. And the Melling HV's reportedly come with the higher pressure spring.

What rockers? The oil to the heads and rocker shafts is 'interruptor' restricted and the restrictions in that path tend to be come increasingly restricted at sustained high RPM's like in circle track use; that is one common problem for sustained running at higher RPM's is the pushrod cups burning up in adjustable rockers.

#4 main gets starved under certain circumstances; reports are that it is due to excessive oil velocity past that oiling passage, if total oil demand gets past a certain level. The crossover is one of the solutions.

As for the pickups, stop and think about one thing: Once the pressure relief spring opens, nothing in the pump area or pickup increases flow into the engine by itself; it takes changes in the engine as a restriction to make the oil flow change (which could happen versus RPM).