You can use rods and wires and a garden hose if you wish, the pressure washer replaces muscle power with water power.
If you have the block on an engine stand so you can rotate it, things flush out more easily. If not, just put it on the floor upside down (on blocks) and laying on it's sides.
One thing that I find helps is to run drill bits through all the block to head cooling holes to remove the rust and open them up to full size, lets bigger pieces fall out. Do the same when flushing the head.
