Originally Posted by HeartCumpton
Are you referring to the breather that sits on top of the intake manifold?
Don't know what all you plan to get into with the flat head, but you gotta check out this info I found. I think you will find it helpful.
First pic of the engine, I would think the oil should go in the breather cap. I only owned one flat head, (willys jeep), and that was probably 25 years ago. My memory has probably faded. If you pull the cap, you should be able to tell if that is where the oil goes.
Let us know how you make out with it.