Sorry for the news..makes me think twice about adding that much power to the Z. Once you do the engine, then everything attached needs to be beefed up. Sort of the knee bone is connected to the leg bone, etc...
I have a friend at work with a nice TT 350Z, and we did some track time last weekend and he was definitely faster due to his extra 100HP to the wheels, but at any time, she can go boom!
Hope you get everything sorted out and good luck with your decision to rebuild.
PS...I still would love to go FI on my 40th
even with the possibility of catastrophic failure.