If you are referring to the V8 small block "Buick" heads used in Winston Cup, I beleive they were built by Dart for Buick.
Buick (GM) did all the castings for S2 blocks. I remember wandering around in the lower levels of Buick Engineering (Building 94) and seeing pallets of S2 heads and blocks. I also saw lots of interesting "Engineering" vehicles.
So are you saying that the picture here, which is of a 1994 Lumina Busch Grand National engine bay with Brodix (pontiac) intake, would be Brodix heads and a Chevy V6?