Gibbo (sorry been busy all day so only just seen the vids and pics).
You really need to either strip the engine down, and get everything cleaned out, or find a way to flush all the oil ways through (including crank journals) as you can't be sure the oil filter caught all the debis (oil coolers can be a bitch for storing debris too).
Last thing you want to do, is fit new shells only for there to be some crap stuck somewhere that will cause more damage when you get it running again.
Strong reading from your M3 - congrats

Has it been modded - i'm guessing so as I'm yet to hear of an E46 M3 that made more power than the quoted figure!