i can't remember if i've managed to restrict the oil feed in the pedestal or not, i won't say it's out of the question. depending on the diameter you can often just tap to a standard size. i normally install the restrictions on the deck surface of the head using a setscrew drilled to .060" and groove the fourth cam journal. on B1 heads i put the restriction under the rocker stand. i would not plug any oil feed holes in the valve gear they're there for a reason. i have tried larger than .060" and it put too much oil up top. people get concerned about starving the rotating assembly, imho this should never be an issue. if it is there's something else that's not right. remember oil does more than lubricate it also cools and cleans.