Really, I'm not trying to discourage anyone from autox, and I don't know you're entire build plan. If you've done the research, and are ready to build a dominating SVT, more power to you.
On the other hand, if you were thinking, "man, my SVT handles well, I bet if I made 250whp I would dominate at autox", you're in for a shock when you're classed with a twin charged EG civic with 600lb springs and three way motons, and then get beat by 5 seconds.
...of course, a turbo'd SVT would be a blast to drive, especially at autox or on the track, just not the fastest thing out there.
So... I'll let the OP come back and fill us in on his goals and budget.
Parking Lot Hero
2008 WRX daily driver
2003 ZX3 23D Autox Car 42 FSP
"Hella Functional - Raced, Not Hard Parked"