Chip, are you using rocker shafts with the flat spot ground the full length? If so that will create a path from the shaft oil hole to the groove in the rocker allowing to much oil to pass. I just ran into this on a 61 engine recently. On that job I brazed the oil connector tube closed where it goes in the head and then drilled it with a 1/16" drill to make it more like the pre 59 flow design.
