Location for oil holes on rocker arms?

I suggest pulling off one of the rocker arms and checking if they reposition the oil hole as Yellow Rose has suggested. May save you some drilling.

Here are a few shots of a Crane small block roller rocker and a Mopar W2 rocker arm. The Crane and many other roller rockers have the oil hole right behind the roller tip to spray oil on the roller and valve stem. The W2 iron rocker repositioned the oil hole in the valve spring pocket to put oil on the spring and valve tip rather than running down the rocker to the top like the OEM 273 mechanical rockers