*I Think* that the big AN line is tapped off the rear main oilk feed to run oil to the front to feed thge oil galley front and rear at the same time while the smaller line(s) are feeding the passage up to the rockers. That is what *I Think* I see.
Awiting the Pit/racers response on that and cam specs.
If the mod was done the way Sanborn recommended, that big line goes to the back of the block and passes through the block to the front oil galley. But I agree we need more pics.