I mention the clearance of the rocker hold down bolt to the rocker shaft mounting holes because it is one of the 3 restrictions in series in the supply to the rocker shaft that are in the same range of size. It is not a matter of it being a problem as much as one to be aware of. In fact, the PRW AL rocker shafts that we have in our 340 have the shaft mounting hole SMALLER than the stock shaft's mounting hole, and that hole's clearance to the rocker mounting bolt/stud becomes the primary oil flow restriction to the rocker shafts in that particular setup.