Welllll
If you want my honest oppinion... Im just scraping $30k spent now including the cost of the car, and I havent got to the engine yet, or ANY body work. Its all been repairs (anything repaired/replaced got the best upgrade I could afford and or felt the car needed) that and $4-6k of stereo, no idea I stopped keeping track.
And Im guessing if you buy a stock rb20e (de) auto, you would last all of 2 weeks before cracking it and going all out.
Best bet, get something you cant or really just wont waste money on and save like a mofo for that year, then buy the car, go to town on it ALL AT ONCE and it will work out at your calculation (ps you forgot the $3k blow out of costs addition). If not you'll end up like me .