The 848 head I cut up was a 235 version that did not have steam holes however I cut it right where they would be which clearly shows that the 3 holes nearest the plug side are unlikely to intersect the jacket if drilled perpendicular to the face. Angling the drill a bit toward the manifold side will increase chances of coolant flow considerably. The 848 head album in my signature has a clear cross section picture and if you go in further than 7/8” you are drilling into the port roof.
