Factory blocks are always a crap shoot. That is why I refuse to pay more than a few hundred bucks for a core engine. The year doesn't matter and neither does the HP stamp. You just have to buy the blocks and spend the time to clean them up and then you find out if it is good or not.

Good news is that 400 blocks are still fairly easy to find. I'm sure you could find one within a week on craigslist.