The newer car is always better starting ground. I say buy the '03-'04 and start saving for mods. From what I understood from your other thread I responded to, your technical knowledge on the subject seems limited and it’s looking a lot like a project car may be a little over your head right now. You might as well start from scratch with the newer car, then while you spend time increasing your cash flow, spend an equal amount of time researching and reading up on what makes these cars tick/go fast.
By the time you’ve got a good grasp on the subject, you’ll still have a car that’s worth something and is still in decent shape to play with.