if you have a battery charger u can take off the wires on the starter and hook up the charger right to the starter this is just 1 way of checking it but if it works right like this you know its not the starter
your catalytic converter is not working to the factory Standard its not really some thing to worry about it doesn't have that much of a affect on your car if just has to do with your exhaust on your car as long as your car isnt boging down when you give it gas then its ok
they only way it will bolt up to the trany and be right is to put the same motor back in that came out you can buy adaptor plats if you don't want to put the same motor back in if you dont know the motor size look on the by the hood release or on the under side of the hood if should say if not...