We had a very large magnet (industrial rated to around 500 pds of force) that we would set our drives on in these instances...whiped them so clean that you needed a low level format to get the mworking again...the data would never be recovered

How much monyis the party woh ould be trying to recover this disk be willing to spend on it ...a fdisk or low level format would basily whipe the disk, and cost a bundle to recover data from.