[Ggmac]

When you first built your motor , did you use coat hangers or something like it to get way down in the bottom of the block ? I found so much debris way down , even after many flushing cycles . I even used the pressure washer. Nothing got to the bottom crusty debris until I used a coat hangers or something ( or something flexible but still strong enough) to get to the bottom.
The rusty internal piece could be from the time you had a head gasket issue.