In a word, NO.
I know that's not what you want to hear, but its what I've discovered over the past few years of working on these cars. I got my first 240 when I was 14, and within the first few months was thinking exactly what you are. Now nearly 10 years later I've been through a couple of 240's and I'm still only finally getting close to my original goals as a teenager, and I can't even begin to add up the amount of money I've spent between all my projects, safe to say WAY more than $5,000, and a hell of a lot more than the cars are actually worth lol.
Here's what happens: you say ok I have this car and this much money, so you poke around the internet and make a nice pretty shopping list of all the things you need to get to your goals, right? WRONG! You will never be able to anticipate EVERY little piece of the puzzle, and more than that, every little setback that will cause you to have to spend money in areas you didn't expect. Hell just last week I spent over $100 just on little fittings and hoses to finish up details like heater hoses, coolant lines, oil lines and other little stuff you don't even think to consider when you're making those little shopping lists... And that's just last week, it was the same story the week before, and two weeks before that etc etc...
Also take this into account: you're (pretty much) 18, what are you going to be doing this time next year, or the year after that? College? Tech school? Working full time? Where are you going to be living? At home? Dorms? Your own apartment? Will you have a place to work on that car wherever you go? Do you really want to devote a great deal of your time and (damn near) all of your money on a long term project during a time in your life when your priorities are gong to be changing at a million miles an hour?
So here's my advice to you, if you want to go fast, take the 5G's (btw do you already have that cash in hand, or is that another hypothetical?) and buy a car that already does everything you want it to do. If you really want a 240, you can make it very nice, clean and reliable for that amount, but don't be out trying to beat the rich kids in school with their Evo's, STI's and Corvette's. Instead set goals you can realistically achieve; a semi-quick, very clean, tasteful, nice handling 240 is very doable for under 5K. And spend the rest of your time and money (the majority) studying, booze and trying to get laid like everyone else in high school
But seriously, have fun while you're young, take on a big project when you have a more stable situation.
But then again... I wouldn't have taken this advise at 17, so I don't expect you to either...
