[brainsboy]

600hp is nothing for a 69 351w block, I have ran this kind of HP all day long on a stock block. I am currently working on a 700-750hp stock 69block now, no big deal. For what its worth although not all 69 blocks are casted the same, if you get a GOOD casted block, the key word here being GOOD, it will hold up to 900-950hp. They break just over 1000, I have done it. You can check the casting by looking at where the cam journals were machined and drilling into the block webbing to check thickness, you would be suprised how much the same 69 block varys.