Having just built my GTO to make over 500 AWHP, let me pass on a little bit of advice. Be smart, take your time and listen to those who know about this platform. I spent so much more than I should have, and went with a setup that may or may not be good. I thought it wouldn't take much longer than a month or two. Almost 2 years later, I'm still not running the G hard. It took almost a year to get her built and back on the road. It was a full custom job which took lots longer, as most custom jobs do. I'm hoping to have mine tuned this week so I will see whether it was all worth it.
Scotty