Since the 400 cid crankshafts are "externally" balanced, you will have to find a fly wheel with counterweights. I've never seen a 400 sb with the manual trans application. I know they were used in some trucks with auto trans. It was also used in the Caprice. It was an option in the '73-'75 Laguna S-3's. You may have to drill and tap the hole, and, find a manual trans flywheel counterbalance kit. If the flywheel or flexplate is not counterbalanced, you can damage the engine.
Jim Sgrig "Piewagn"
