I don't know about that head swap info...but....I drilled the steam holes on a #848 235 head.Drilled them straight in too,no problem.Ran that head on that engine for 5 years.
Panic mentions potential oiling problems when mixing rockers arms and such....Yes,bottom line from my experience is a .062 restriction must be somewhere in the feed to the rocker arms.That's the same size used by GMC which is located in the oil line fitting to the head.
