Having talked to this guy and see it run not only on the dyno but on I-70 west I can attest to the holy-f**kery going on with this thing. And it's all 2nd hand parts. 719rwhp was the low end.. if I recall it wound up punching 750 and was capable of more.
5.3 heads
230ish comp cam
Turbo set up was 900 bucks
Welded truck manis
Stock 99 block