Hi Sadie,
My relatives arrived in Maryborough aboard the Tim Whiffler arriving 16 June 1875. Unfortunately they were the Turner clan and not Bell. However, and please forgive me if you already know this, but I would definitely check with the lovely people at the Maryborough Historical Society - Family Genealogy group. I understand that there is a reunion being organized for the descendent passengers of the Tim Whiffler's 1874 arrival ...and there were only two transits before she sunk.
The Historical Society have also put together an inexpensive booklet on the Tim Whiffler. I recall it has full passenger lists for both journeys but primarily relates to the ship's first (1874) voyage. Of real interest is a partial account by a passenger of the voyage from UK to Maryborough and some insights into the thoughts and feelings of that immigrant...The booklet is also available in the John Oxley Library in Brisbane.
Having grown up in Maryborough I can also confirm that there are a great many 'Bell' around. Indeed I actually lived in Bell Street on the Bell Hilltop estate. I would be confident that there would be those in the Society who might be able to point you in the right direction...
Hope this helps you in some small way on your quest!
Cheers
Glenys