If you have a car that runs, leave it alone and enjoy.
Do some research and search, you have the time, find a 64 1/2 original first year of the Mustang and buy a convertible with ALL the options, or the first year of a particular model with ALL the options. Put it in dry storage, you have the start of an investment.
Now, save money and as you get a little, buy and dry store an original part you will need to restore the baby in the garage. When you are out of the service, get some more education if you want / need, get a good job. Get married and have some kids.
Now when the wife is off shopping and the kids are able to take care of themselves somewhat, you have a toy to play with, paid for, all the parts you need and something to occupy your time and the $$$$ to take care of those little things you did not think of. You will end up with a fully restored original Mustang convertible. A great investment and you have some fun.
I know, you want to do it now, well wait and it will result in a great payoff.
Point is, if you are going to redo a car, get one unique in year or model with all the factory options installed you can on it. As you restore you will not want to wait until you get more money to do something. The anticipation will kill you as it is slowly coming together. Having the ready cash and being able to afford it is more fun, less stress. With the economy "hesitating" I would keep an eye out, look in Hemmings. You never know when someone just "has" to get rid of a car.