Junkyard 5.9L Magnum + Edelbrock LA heads build

FWIW, those larger holes around bottom holes 2 or 4, when a bolt is inserted, have a smaller flow area that the rocker oiling passage passage up through the LA head or block, or the oil passage through the cam. I suspect you are right in thinking you are going to use a far smaller flow area with the full oil pressure going into this feed. A .100" diameter restrictor would have an open area about 1/4 of the area of the more open shaft hole with a bolt through it, so the smaller shaft holes will be an even more noticeable added restriction. Just be aware it is there, so that something like the shaft shifting a bit when mounted does not come into the picture.

I look forward to seeing how this works out!