Even "seasoned" 302 factory blocks are only good to about 500 at the tires. They have this issue of splitting throught the mains. I have two with that issue sitting in the floor here. I know companies like DSS claim they do special stuff to make them live longer but, in reality you can't change the casting strength. To go further you need either a original Boss 302 block, new Ford racing Boss 302 block, A4, R302, or Dart block. You can get by with a Mexican block if you don't plan on going past about 650 rwhp. I have one of the rare mexican 351 blocks! Bad thing is that it isn't any stronger than a 70 model 351w block.