First Time Help

[Sn4zzle]

So I am turning 16 in a few months and plan to get a job when I turn 16. My grandmother said she will give me a few thousand towards my first car so if I can pick up a job and get another few thousand that way I would have roughly $6-$7k. Now with that much I should be able to get a car and I am looking at a mazda rx7 FC, Supra mkII, ae86 (if I can find one) or a 240sx. Now we do have local drift competitions that you need to be 18 to compete in so I may do that in 2 years but for now what would be the best car out of these to get? I will have a job before I get a car so I am going to play on changing the suspension in my car no matter what. Basically I am thinking change out; struts, coilovers, coilover bar, sway bars, break pads, lightened flywheel, better clutch. I may change out the intake/exhaust system but for now that would be the stuff I plan to change out. What would you guys think would be the best platform to pick up?