If he is restricting the oil at the cam bearings by drilling a hole and turning the bearing if he does that on number two and number 4 he is blocking oil supply to the cylinder heads. Therefore he would need a crossover tube to feed oil to the driver side head port or channel whatever you want to call it or drill through the channel into the main galley and then plug the outside hole to get oil up to the cylinder head. That is if he is blocking the oil passage down at the cam.
The crossover tube to feed the number one main bearing is not the same as the crossover to feed the heads.
