Thanks, Dave. Your overview cleared up my confusion, however, once I got under the car, I didn't bother. The left side (cylinders 1 & 3) was almost bone dry around the tubes and valve cover. There does appear some oil at the cylinder base and head joints.
The right side (cylinders 2 & 4) was an oily mess.
Valve cover and one or two push rod tubes may be partly to blame, but, again, it seems it's coming from the cylinder base and head joints.
Decided to just set the valves (gee, what an ordeal. I'm definitely marking the flywheel when I have the chance), replaced the valve cover gaskets and called it a day.
