Becareful of changing the nozzles of spray cans. What will happen is that you will change the flow of the paint leaving the can. this means that the paint will be very difficult to control leading to runs. Also if the nozzle is to big the paint will no longer atomize. That means that the paint would flow in a constant stream. Air brushes are becoming very inexpensive and you can use can air if you can't afford an compresser. You will find that the more you use the airbrush the wasted paint you have with canned paint.
Good luck