Yeah I would think your Shelby is around 850whp, and like you said, if you take good care of it and the tune is dialed in, the engine should live a long happy life.Theoretically, we can push this stock 5.8 block to 1000whp as many have haha, especially in how you drive it etc. I have certainly pushed mine farther than what one would drag race this car quite often. Keeping the rpms at or below 6200, good fuel and tune you can push her where ever you desire (NOT RECOMMENDED)..I have yet to get this new setup to a legit dyno, but I know you have hit low 800s to the wheel with just a 3.5 upper.. I have almost a full 1/2" smaller pulley than what you ran, so I am playing with fire so to speak and I know this. Hence why my car only has 5,600 miles on it.