Mint 1973 Ford Mustang Coupe?
These two cars are very much sought after right now, but yours are worth a WHOLE LOT more than most of them out there now cause they have been restored. The best thing you could do is like was said before, insure the heck out of them. Keep in mind that your insurance agent will want to look at them. Im not sure who to tell you to contact about the values of the cars, but you could try Kelly Blue Book or something like that. You may be able to find a shop that specializes in antique Fords or just antique cars in general. For your 73, New England Mustang Supply is great! I have ordered parts from them before and they are good to deal with.
You need to figure out what their values are as well. Also, it makes them more valuable if all the numbers match. If you plan on keeping them, I would trailer them anywhere you go since they are valuable cars (trailer queen, as I call them). Make sure to keep them garaged whenever possible to keep them from being exposed to the elements.
If these cars have not been driven in a while, I would advise to change the oil and give them a good mechanical check-up. I have a 73 coupe myself (not mint) and do know how it is to have a car this old. They are good at hiding things, trust me! lol Congrats on your new babies and do not let anybody take them from you! I would like to see pics of both cars cause Im sure they are knockouts. You will have people knockin down your door for them.