The mounting bracket is easy enough, anyone who is planning on doing this can have a mounting plate, I made a few extra templates when I was making one to mount my coil (just need to drill the holes to match the LS1 coil pack holes..
500 might be a little high but lets also not forget you will need to pay for a LS1 PCM. So to say all together with everything you need it might run 800 is not out of the questions and thats like the price of 2 or 3 new opti's depending on where you buy them from.