I have a similar question.
I paid some serious cash for a complete rebuild on my engine, it has sat in a crate for the ten years since, but been turned by hand regularly and it was full of graphogen paste.
I have been gradually checking things over and running the engine up slowly checking things over as I go. I now have what I consider to be a significant amount of oil running down the left barrel fins, shining a light into the gap between barrel and head shows a few bubbles popping from the head gasket while the engine is idling. I cant see any leak around the rocker gasket seals which leads me to believe it is the head gasket. And if it is the head gasket, where is the oil likely to be coming from? The only oil way is the pushrod channel, correct?
As yet the engine has not been under any load, I run it up to warm, checking the fuelling, idling timing etc.
It is entirely possible the head bolts simply need a re-torque, or it might be something more serious.
As a start, does anybody have the correct torque settings ( or know where I can find them ) for a 1957 plunger engine. They don't seem to be in the Haynes manual.
If that fails then I am into a complete strip down, in which case I am going to be in a right grump.