I dont know if they offered ac on 67 BB cars but you could change the inner side of the box and that would work, as far as what else you would have to change of course would be the frame mounts,springs, and hoses, like you said. You can run stock manifolds without a problem and and use the same steering box but if you have PS you have to change the pump and hoses,brackets. If you have a 4 speed you might have to change the shifter bracket on the trans because the engine sets over towards the pass side of the car.If anyone else has more info please speak up.