Well, its an iron block, you will probably never destroy it, i'd be more concerned about the rings and pistons, the rods are pretty strong too.
I'm gonna push 12 psi in my 2.0L (it's at 8 psi right now) and i know someone with the same engine pushing 13.5 psi on a bone stock motor.
They are strong engines if you are carefull and know what you are doing.