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

Right. Like I said why is any oil going to the drivers side unless you run hydraulic lifters or pushrod oil?

The answer is there is no reason to. And as I said, there are far better ways to get oil to the lifters or pushrods than that stupid crossover regardless of the angles it’s fitted at.
The reason is to reverse feed number one main. The tube is only one part of the modification. It is just a better distribution of the supply oil.