I hear ya. I understand where your coming from financially. There is a ton of things I want to do with my six, as well as purchase another mustang (v8 preferrably), but school comes first.
Since you already have the motor, you have a couple of options:
1. You could go ahead with the swap. Do some research and see what you would need to make the 302 work. It's EFI so that makes it easier. I would guess the hardest parts would be the wiring, ECU working in your car to relay info, and the connection to the tranny. (If you're using the mustang tranny)
2. Sell the 302, slowly save up some money to either boost your current engine, or purchase a v8 car (though I would imagine you wouldn't want to do this, as you stated before)
3. Keep the 302 for now, just drive the stang as is (maybe put a couple bolt-on mods for some amusement), finish school, then buy another car as a daily driver (stang possibly
). Make the 302and the v6 stang a project car.
Hopefully some of the more experienced guys will reply about the 302 swap.