The breather tank (?) you are attempting to make can also be made very neatly with by salvaging a pair of empty small fire extinguishers and cutting them apart. They have a formed bottom and look quite nice. The tubes going into them from the engine are usually 3/4". The cap and threaded bung can be had from some of the vendors that modify 9" Ford rear ends, they are used as a means to fill the
oil into the axle housing . I think a current spec radiator with provisions for transmission
oil to be plumbed into it as a means of cooling is a very good efficient alternative to an air to
oil cooler. That being said the oil coolers used in the nose of the Cobras are about 13 inches between the hose fittings and 4 inches tall.
It is a nice little welding project.
Rick