Given the age of your tractor, it'll me darn near imposable. But, if you can find a company that will allow you to lease on and pull rail, I'd jump at it... Given that Chicago has a lot of rail freight, that would be your best bet. You may want to try your local steel and salvage companies, a lot of time they will have a lot of intrastate(in state) work, granted you will need your own trailer(not necessarily a flat) and authority, but it's an option down the road... My dad owns a steel company, and 80% of the drivers that go in there have contracts with my father. Look at the types of businesses around you to determine what type freight you should haul...
Actually container companies don't care about the year of the truck as long as it'll pass dot inspection.
Save your money and go to school...... I was there and did it outlaw style at your age, no one will lease you on.
Double L, I think you should listen to this advice... While I am sure you have done a lot of research on the subject, it's important to remember that experience is something you get by doing, not by reading... Please don't take this as an insult, I just don't want to see you get in over your head. Good Luck.