CDC Lark drive and SMD Interface

Hi I have data I would like to restore from a CDC Lark pack. It's actually an OS disk from a British machine called the Molecular 18. I have a working Lark drive, happily several disk packs, but no original machine. I do have a PDP11/73 with a very flexible SMD controller - the Webster WQSMD. I know nothing about the actual disk structure on the packs, other than a vague recollection that the packs were hard sectored. The WQSMD is detecting whether the drive is idle or up to speed. Making random guesses to the disk structure isn't working - my hope was to guess and use the WQSMD option of reading raw disk blocks. I am taking to the WQSMD directly - using the 11/73 simply as the power supply! Any thoughts or suggestions as pursuing this path or finding another. Regards Kevin