Very wise man. I had a 650hp fox body mustang in high school and one day when I was on my way home, it started to sprinkle. The back wheels decided they wanted to be in front and all I could do was hold on. True story and that lead to me selling the car and buying my first Honda (well that and getting right around 8 mpg).Know some one with a 600hp Neon and when you get pedal happy on the freeway(which you will) you are going to have the front wheels break loose and drift into either other cars, barriers, or the ditch, and loose your rather large investment and have increased insurance rates due to the accedent. There is nothing wrong with 500HP to the wheels on a FWD car but there is a place, and driving ability for it. I'm not trying to insult you or anything but riding in that neon was scary. The Idea of getting a B18 and building around 250 to 300 would be good till you get alot more skill behind the wheel, and will also be able to build from later on.
Just my $.02
Build in stages, but keep safety in mind. Don't go all out on you engine and forget your brakes and suspension. How about a basic B swap to get you started. Go to your local auto parts store and get a set of Loaded Front Calipers for a GSR and slotted and drilled rotors for a GSR off the internet to get the brakes up to the task of handling the new found power. Do so research and find a good strut and spring combo. Don't go jumping off the high dive when you are still treading water. Be honest, do you need 4-500hp. Its like trying to hammer in nail with a jack hammer!