What are D-100 doors? Are you refering to one-piece doors found on Defender station wagons?
If so, yes, the FG top will fit. Several members on this board have done it. Are the one-piece doors on your Defender now? One-piece SW doors and two-piece ST doors are interchangeable, however the strike plates need to be swapped. A year or so ago, Copely Motorcars sold a Defender fitted with a ST with two-piece doors and a FG hard top with one-piece doors.
Also, if not already done, I believe 94's require rivnuts need to be installed on the tub cappings.