where matching numbers is good is when buying a used car.if the police find a "HOT" engine or transmission in your vehicle, you just lost your car.and you will probably be charged with posession of stolen property.
there's a thriving market for old muscle car ownerships,keys ,locks,and serial numbers(dash).they're that lazy now that they steal a car , buy a matching set of the above off a wreck,swap the windshield(and numbers)and send the car away to be sold.they don't even paint them.
i think matching serial numbers is an important thing unless you did the "unmatching" mike