Uggg. You are way too caught up in stock numbers. And just so you know, car guys don't use flywheel hp numbers anyways.
Do you know the difference between an LS1 and an LS6? The quoted statement just seems ignorant. If you are worried about what GM said the engine made, than buy the LS6... The LS2 will make more power stock, as well as mod for mod, but it would not be worth the extra money to me. You can get 450rwhp out of an LS1 easily, and that is plenty for a street car that weighs less than 3000lbs. There are several people that have gotten 500rwhp out of the LS1 on a stock bottom end.