B/C-body Exhaust Manifolds, why won’t those work in A’s.

in a nutshell, what issues come into play that keep from using b/c-body manifolds in a-body cars? Anyone have pics of the clearance issues? Is the column completely in the way? Have a friend here who wants to build a big block car, but has every part to do it except the exhaust manifolds and a budget that makes a paperboy look rich. Any info or possible pics of the issue(s) would be appreciated.