I believe the turbo engines made around 210-220 hp stock with a tiny turbo and no intercooler. From what I gather if you size up your fuel delivery system, retune ecu, exhaust, and add some boost you should get fairly close to 300 no problem. That being said, this all on top of swapping this engine in first place. I like this motor mainly because it's fairly simple, really overbuilt, and tiny.
Its no lsx motor in terms of bang for the buck, but it does have a character all it's own. I'm guessing the guy in that article did alot of that to his engine for the same reason I would-because it looks cool as hell!