If you plumb direct into the shaft, then you'll need to put a restriction in that line somewhere or it may over-oil the rockers and take pressure from the main system. The main flow restriction point in the LA system is where the rocker bolts down to the particular stand where the oil come up; the hole in the shaft and the bolt going through form the smallest (and controlling) restriction point in the flow path to the rockers.
BTW, I would take it from the passenger side gallery; I would expect more consistent pressure there.