I actually imagine a factory based short block could handle it for awhile but I have no basis of experience to back up that assumption. Most folks suggest the block will let go north of 600 hp.
I've got dyno sheets and an engine that says otherwise. 650 hp 408 with a Procharger. But I understand the boost comes on gradually so it's not just like a 650 hp NA motor. It's why I suggested a stud girdle like what's in my 408.
