Not a normal flathead crack area. It's usually at the center two cylinders, across the valve seats and on each side as the exhaust is siamesed. Not an unusual occurrence for a flathead to have one or more cracks, sleeves installed and/or metal stitching at the valve seat area.

Your biggest problem now - to find someone locally that has a sleeve press and know how to use it AFTER you find someone that even knows what you are talking about