For anyone that gives a plop, dorman makes a repro pan with the stick going directly into the pan. This way you can pretty much run any SBC in any chassis with any exhaust manifolds:
http://www.dormanproducts.com/p-2022-264-118.aspx
The 78-(and 79?) malibus/elcaminos and i think monte carlos had this pan for emmission reasons i think?
You can clearly see in the picture that the stick goes directly into the pan.