oil change on my 360

yeah, I don't much like those large slivers. I have been a big proponent of the FilterMag filter magnets. I've cut apart many filters and I've only found a fine, dark colored "fur", no large slivers. But, I've never run them on a fresh build, either.
Q1; did you do any grinding on the head or block that could possibly show up like this?
Q2; did you do the assembly on this short block, or long block?
Q3; how were the block and heads cleaned before assembly?