No help sorry just that I have to ask what on earth did you fill the 160GB with ...? Just that I have a very modest 18GB on my A4000/040d and it like is never going to get full even with a full back up of my 13000 floppy disks that I have. That's some capacity you are aiming for. I don't think there is that much Amiga data in the known universe. Thats like 550000 DD disks for a 500GB. Incredible!
Anyways I'm sure someone here will help you. Have fun.
PS I do have 40GB drives on a number of my 1200s. But I only use 4GB of them.' As you do.'