go for it!
I spent my graduation money on my car a few years ago and it was well worth it.
One thing though that I'm sure you already know. When you obtain a motor, make sure you tear it down and have everything inspected. New bearings, bolts, rings.....
The guy that I sold my AOD to did the 4cyl swap with a 5.0 motor that he got for like $200 bucks. he thought it was in good shape so he just carb'd it and slapped it in there. As soon as he fired it up it shot a few gallons of coolant out the tail pipes. Also, he's recently found out that a rod is knocking pretty bad.
Just thought I'd try to save you some headaches, but I'm sure you're not THAT dumb
good luck with it man,
-Drew