Dan,
Here is Southern's link.
http://www.southernrods.com/
Look at the heating and cooling link.
I have used their universal kit in a 66 nova I built before Vintage Air had their kit available. Their system worked great and it was an a/c and heat unit. I have since viewed the vintage air system for the novas and they look very similiar in appearance. Hope the link is what you were looking for.
BB
P.S. I posted this over at PT.com too.