It depends on if you are talking about stock displacement or Strokers, most head/cam LT 1/4cars I see that really perform good are up near the 400rwhp mark and I have seen quite a few LS 1/6 cars make 420-440 rwhp now if your talking stroker motors you could certainly see close to 500 rwhp. This is all naturally asperated, add blower, turbo or nitrous and the tables really turn
I have a friend with a 1996 LT-1 SS Camaro with a 396 stroker that makes 471 rwhp and that was with a bad opti spark.