most will run a whipple/kb/turbo for a bit, and upgrade the shortblock before something happens. i think the limiting point where you can consider it "safe" somewhat, is around 500 rwhp.
of course there is lots of variables with timing, how many pounds, how hard you drive it, ect.
i personally wouldnt expect it to last much past 500 rwhp without wondering when she will let go. opinions will vary alot on this, because some people have run 600 rwhp for awhile with no problems. some have blown up on stock cars.