It really depends on the state of the chassis and drivetrain. If everything else is in decent shape, around $500, max.

I'd also take everything the seller says with a full shaker of salt, seeing as how he managed to throw a rod through the block. I'll put it to you this way. When buying a car that a previous owner has managed to grenade, do you trust that there aren't five million other problems or half-assed repairs?