^^^^^so everyone who says their small block is 500 or 600hp is lying? There's lots of BS-ers for sure but that's quite the blanket statement, especially since it's wrong. 605 dynoed HP right here, 2500miles of street and hiway, plus .5 miles of track time :)
To the OP, I agree with others that you aren't going to be near 500Hp yet, with that being said I'd say it still wouldn't be wise to spray more then 100 if you want any sort of life out of your build. If you originally planned to spray, why not put the extra bux into forged parts?