Verifying mileage is really tough, unless you can find maintenence or repair receipts that are dated and show mileage. Depending upon where the car spent most of its life, just great condition will go a long way towards low mileage being believable. If the car is a Michigan car, simply having the body survive intact would be a testament to the fact that it didn’t go vary far, at least in the winter. Also things like the little paper tags and crayon and chalk marks still be ing in place that were placed by the factory, except that there are some fanatic restorers who will put them on. With a 61 Comet, the car is not such a high value car that I would expect someone would go to that kind of trouble.