727 46RH conversion coming
Somebody should make a piece of 1/4" steel plate that fits snug up against the floor after the top of the crossmember is cut completely out. Say, about 8" from front to back, and fitting all the way down to bottom of the side stubs. So you'd cut the side members at an angle to match the tunnel, about 45 degrees, and weld the plate to the stubs and to the floor.