440 hp with stock block?

It can do it but it's a matter of time. Like was said 600-650 with a wet block is about it. The block's main webbing will eventually fail either with a crack accross a main or catastrophically. Truthfully a new better block is only about $1500 more than properly prepping a factory block and it will last forever. If you're going to reach that high a level this should not be a problem.