I just wanted help in this situation with the Factory rating.. cause they are under rating them to save their azzes due to some idiots who can't tune..... Like I said I have a friend that has a 302 stock block, rods, crank, cam, performer rshared_pm intake , and a stage 1 HP 60mm turbo kit that made over 500hp and running strong with no issues at all. I ran 6.20's with a stock block.. 125 shot on a 347 w/powerglyde in a stock block girdled. Make sure your tune is safe before hand and it will live if you will.... stock block (will for sure ) hold more than 500hp and a sportsman (will) hold 800+ girdled and grouted with no probs if your tune is safe. Even if you had a r block or a boss block it will screw up too if your tune is way off and you detonate it...