You posted another thread about wiring for your LS1 swap and didn't really get any responses, and I'm afraid that's what you're looking at again. It's such a rare thing done that you need to find somebody that's done it before in order to get your questions answered. Anything anybody here tells you I wouldn't trust unless they've actually done it. I know a lot about cars, wiring, engines, and all sorts of things but I still wouldn't try and give you advice on such a swap.
On a side note, a couple of questions if you'd answer them:
1. Why did you decide to do this swap? Why not go with an STI short block or just build out a regular WRX block with a big turbo or something like that?
2. Do you know anyone that's done this swap, whether personally or somebody you've met or even just read about on a forum or other internet site?
3. Do you have any pictures of the progress so far?
4. What's involved in doing this? Are you running a GM tranny with the LS1? What's the running gear on the car (axles, hubs, suspension, etc)?
5. Besides the engine, what else are you changing?
6. What's the goal for this car? Is it going to be a drag car, daily driver, weekend toy, etc?
7. What do you think the final cost of this swap will be?
8. Is this going to be AWD or RWD?
Thanks in advance for whatever info you're willing to share!