Depends on how long you want it to last and what you're doing to get it there. How high you're reving it, ect.
Stock bottom ends will take a couple 1k smacks and hold fine. There are many 7-800 horse B's runnin round out there with stock guts that are just fine too. I don't think any have puked on the dyno.
Get too far north of 1k with repeated floggin'and you better have a contingency plain in place. :hehe: My .02