The drill and tap in the heads is the approach I've taken with my W2 Econo's setup and Harland Sharp roller needle rocker arms.
HS specifically advised to limit the oil flow to the rockers, but not knowing what the right fit is for a street ride I figured I would play it safe by prepping for adjustability: if too much oil flows, I'll scale back in the size of the orifice, and all it takes is pulling the rocker arm shafts off and replacing the plug, as opposed to having to yank the heads off the block!