hard or soft copper line for a valley oil gallery bypass line?

That's correct. You can have pressure and no flow, and we have remember that these engines are over pumped. Well most of them are anyway and probably should be. At low engine speeds with a big pump and not much oiling moving through the engine you can have pressure and no flow.
If you have pressure with no flow, then you have a sealed system. If you have pressure and oil moving through the system then you have flow.


If you want me to tell you the crossover is some magic bullet I won't because its not
I haven't mentioned the cross over hose.