If the 73 degrees of the Cinelli stem is representative of quill stems and 73 degrees is a representative head angle of your typical horizontal top tube frame then geometry tells you that the two will be parallel.
If I could embed a drawing here then I could show you.
If the 73 degrees of the Cinelli stem is representative of quill stems and 73 degrees is a representative head angle of your typical horizontal top tube frame then geometry tells you that the two will be parallel.
If I could embed a drawing here then I could show you.