this is how I would manage your situation:
an NTFS filesystem does not carry per-file owner and group information the way Linux expects, as native *nix filesystems does. So when you mount it the system must somehow concoct an owner and a group for every file on the volume. While the system can pick an appropriate default you can specify those values when mounting, via the uid=<username>
mount options. That way every file and directory on that volume will appear as if they were owned by <username> and had a group of <groupname>.
Now, a way you can grant write permission to selected processes only is:
1) create a brand new group on your system, such as usbvolusers
2) when mounting the NTFS drive, specify that group via the gid option, that is gid=usbvolusers
. Now every file and folder on the drive belongs to that group. Also don't forget to specify the options fmask=0117 and dmask=0007: those values prevents "others" from accessing the volume, even read-only, but members of the usbvolusers group will have read/write access to the whole contents.
3) Add each user that needs read/write access to the drive to the usbvolusers group. You should at least add the user the deluge process belongs to (start deluge and use ps to find out) and yourself.
4) Reboot, just to stay safe and start clean
At that point deluge should be able to write torrents there.
we'll find a way!